Unfortunately (because it is hard to watch how lonely many elderly people are), I have spent a lot of time in Care Centers/ Nursing Homes, not for myself thankfully, but visiting parents and relatives. I also worked as a lab tech when I was young and went into Nursing Homes to take X rays and blood samples, I always took time to talk to the people I worked on, the are rich with life experience and really enjoy talking. But, unfortunately I have not performed magic yet for them, it is on my bucket list.
What I can say from my many times in Nursing homes, is that generally elderly people are very appreciative of anyone that comes into entertain them. They will be a very good audience! Take into account they may not hear well...so speak up and don't talk real fast. Also, they may not see well, so keep as close as possible to perform, don't let them stick you up on some stage....walk around would be great, if you are comfortable. Cardistry would be great, but unless you are real close to the audience, basic card tricks may be to small for them to see... Overall, don't fear this audience, unfortunately most folks in Nursing homes are very LONELY, and really appreciate any form of entertainment....go for it and have fun!