If a parent comes to another parent, a volunteer, directly with such a concern about a yearbook matter, refer them to management/staff, LUV has the right idea.

If its hearsay you are basing your conclusion on, most likely its untrue or skewed.

We all know from childhoodand even adulthood how talk/words change quickly and easily from one person to the next, or can easily be misinterpreted when taken out of context.

I would say, if yuo didnt hear the compliant from the alleged SOURCE, chances are, its not true.

And since folks seem to like quotes these days, and have been submitting some great thoughts, heres one I like:

The least initial deviation from the truth is multiplied later a thousandfold. Aristotle

Our school notifies parents at the beginning of the school year that class lists may be provided to the PTO for use with programs and if they do not want their child's name and info released or do not want their child's photo used in any publications to notify the school in writing by a certain date.

If your school has this same policy, I would simply direct the person to the appropriate school personnel. If they don't have this policy, I would recommend it to them or next year make sure that the yearbook committee sends out such a notice.

Unfortunately, there are some people who forget that we are volunteers and are working on projects and events out of the goodness of our hearts and the desire to improve our school. If she jumped me, I'd remind her of that in no uncertain terms, and suggest she bring up issues such as this with the principal.

its about kids .....forgot to mention,,,".the parent actually was angry with the school that the committee was told that the student was not to be included... "
same thought as before, HOW do you know the parent was angry? did they come to you directly or did you hear it third hand???? did you call the parent and clear it up? maybe it was a rumor, you heard someone say they were angry, but they really werent, or some other nuance.

at our school, there have been many many many misunderstnadings among volunteers,,,,all becaseu people believe the grapes on the vine. sometimes all it takes is a simple phone call to the parent in question to get things cleared up and rumor quashed. anyway, hope all worked out, its not worth the headache to think such thoughts of other volunteers, feel they are making your life as a volunteer tough, when you could clear up and get the truth, with a simple phone call (and ask if theyd like to help on the committee, if its a really true issue for them!!!).
its best not to prejudge people based on hearsay (how do you KNOW its the truth???), but to get to know them and decide for yourself if they are a true complainer or if someone is making them out to be acomplainer.
"Beware of the half truth. You may have gotten hold of the wrong half." ~Author Unknown

its about kids ".the parent actually was angry with the school that the committee was told that the student was not to be included... now come on, how are we to know not to include that student?!"
why was there anger about that? how could one otherwise know not to include the photos/not include?
doesnt your form the parents fill out say something like 'this information will be provided to our yearbook committee' or something like that?
even without that, i would think a parent that dosent want their kid in the yearboook, be more than happy that the people putting it together, know not to include their kid.
but even without such a disclaimer, there is something known as 'fair use' and such infos can reasonable be expected to be transmitted to yearbook staff.
you should , as volunteer, nefver be on the receiving end of parent complaints, thats what school staff are for, to act as problem solvers for parent - school matters... sooo, maybe delegate the matter, did you address the head of school? thats what i would do. dont stew over it, its not your responsibilty.
and, how did you learn of the parents 'change of mind'?? did it come DIRECTLY from the parent, or from the administration? any other form of transmission ie hearsay, is strictly untrustworthy. dont believe what yuo hear third hand. if its not from the source or from staff, you may have misunderstood the matter entirely. it happens all the time at our school, misunderstandings among volunteers becuase they listen to the grapevine and believe what they hear. so sad. but it happens.it has cuased tons of stress all due to misunderstandings. people talk to everyone but the one they are talking ABOUT. leads to unnecessary misunderstandings.

its about kids -- "...We are volunteers who are doing our best, we are not getting paid, we do have lives outside of school and I think it not fair to be treated as grunts or have demands thrown at us.." wow i would toss that right on over to your principal, that sounds just awful that you feel that way. since when do parents make demands of other parents? that should never happen. should go thru admin., all parent requests.
we never had issues at our school. at registration, we fill out a form, and that takes care of the matter.
it gets filed with the school, other parents do not have access to the info, the head of school handles the matter as the school has final review process/release say over yearbook matters anyway, in addition to any parents' requests, so if a parent wanted a change mid year, at our school they have to go throught the principal and sign a new form but i have never heard of this happening.
so it seems it would up to the principal to say OK to the parents change of mind , or OOPS,SO SORRY its too late to make a chnage, the yearbook is too far along, etc etc.
doenst seem like this isnt a problem that cant be ironed out between the parent and the principal. wish all school matters were so 'small'.

seems for such matters, they could be addressed / reffered to the principal. volunteers are just that, volunteers. they are not managers in affairs of school business/publishing releases/changes of mind of parents during school year.
maybe if you get such issues in future, just send them up one level.
its not YOUR job as volunteer to interced in matters between parent and school or district.
your job should be free of parent/school matters, they belong in the principals office, or supers office, thats actually the main job of principal, mediating parental issues, and once you get to high school , the pressure is on from the parents (grades..and college,,etc)