What a great family treasure! Its wonderful that you have the story to go with it. The American Institute for Conservation has Find a Conservator to help you find a professional in your area. In addition to the condition issues you noted, some of the pigments used to hand color the print have faded, most notably the yellow which would have been gamboge. F.F. PALMER, DEL. is for the artist and lithographer Frances Flora Palmer (yes, a woman!), DEL. stands for “Delineavit” or drawn by. There is lots published on Currier and Ives and you may be able to get an idea of the date published by the address.

The address dates the print between 1838 and 1872....that's when they were operating out of 152 Nassau Street.
Currier and Ives made prints very cheaply and in great quantity for the every day person.....and used cheap paper and cheap inks....sadly they discolor easily and fade. And but for certain very special large sized historical prints are worth very little. And yours was framed badly....with a wood backing and that's why the discoloration.
The frame is wonderful....but I agree not particularly suited for that print....but Great Grandma liked it so i would leave it.
There is nothing you can do about the discoloration. It's a cheap paper not the fine rag paper that some other lithos might have been printed on.
I would have it backed with a acid free board and put it back into that frame. The print itself might be worth $15....maybe not that much....but the frame about $40.
I wouldn't say I collect Currier and Ives prints, but I do have 5.