Welcome to disABILITIES.
Glad to hear you have gotten some good info already.
Sorry to hear about your mom. I hope she has the same good fortune with her liver cancer as the mother of someone I once worked with. They spent the first 6 months after her diagnosis expecting her to beccome very ill, but when I left that job 5 years later, she was still doing remarkedly well.
I have received a birthday button, so I know those exist. You get them from Guest Services, so I guess if there are any other "I'm Special" buttons, that would be the place to get them too. There is a Guest Services in each park; they are usually close to the entrance and they are well marked on the park maps.
Another thing some people have gotten is "Guest of Honor" nametags. Those are something that you can buy in the gift shops at all the parks. They are similar to the nametags that CMs wear and come pre-engraved with more common names. A lot of people have mentioned that CMs called them by name when they wore these. You could probably get more info about these on the Theme Parks Board.
The other thing I'd suggest is mentioning when you check in to your resort that this is a special trip (usually the special trips people mention are for anniversaries, weddings, etc, but if you can figure out a nice way to explain your situation, go for it).
If your mom has stamina concenrs, I'd suggest renting an
ecv (or wheelchair, if she doesn't want to drive). That would help conserve her energy so she's not using so much energy just getting around, but can save it for the more fun things.
Here's a
page with some helpful hints . I found a few errors on it, but it's generally very good. The errors have to do with renting
ecvs (they are not the same as motorized wheelcahirs) in the parks and parking. It says if you rent an ecv in one park, you can bring it to another park and that is not true as far as I know. It also says that the resort staff can help you get a handicapped parking hangtag if you bring documentation that you need one. That is not true as far as I know. If you don't have a wheelchair or ecv, you are actually better off using the regular parking in most cases if you drive, since the regular parking has trams to take you to the park antrance and the handicapped parking doesn't.