Those are some good practical suggestions.
Some to add that would be more in the sanity saving category:
Roll of quarters and shiny new pennies for pressed pennies.
Disney Dollars to hand out for Mickey Bars.
Those tiny books of word search, crosswords, etc and some pencils.
Is your mom of an age to know how to do cat's cradles? Some string if you think she is...
Maybe a scavenger hunt for them? Although there are the 50 hidden golden mickey's to look for at
Disneyland this summer, maybe you could think of something else for them to be looking for while they wait for the parade, fireworks, etc?
Film, or a memory card, or however she takes photos.
Small snacks like cereal bars, cheerios, etc. Lifesavers, mints, etc.
And maybe you could make a tee shirt that says something like "I Survived a trip to Disneyland with my Grandkids" if that is something she would wear. I know my grandma would wear that to her meeting just so she would get the attention.
Then some small packs of tylenol, those bandaids with the antibacterial on them already, small package of kleenex...etc
And come over to the Disneyland board and print off the list of free things to do and secrets for her as well.
Cute present!