What's a good gift for someone with Alzheimer's?

My mother-in-law is 86 and in perfect health...except for her Alzheimer's dementia and the fact that she has been blind for years. We are going to take a long trip to see her (we go about once a year) and I would love to get her a nice gift, but I am at a loss. She lives at home with my sister-in-law and some occaisional live-in help.