I think it might be best to start with something simple, like a charm-pack lap quilt. (5 inch squares. Or even bigger). Then ask the participants what they want to do. Some of them would probably like to hand quilt, and will need hoops. Some might want to do some applique. Aside from the basic sewing, there are all sorts of possibilities. Also, if the nursing home has an OT (Occupational Therapist), you might consult with her/him. The OT will probably have some good hints about working around physical problems, as well as having useful little tools and gadgets that will make it easier. And remember that seniors will tire long before a younger person, and take longer to recover, so that sessions should probably not be any longer than 45-60 minutes. Follow the KISS principle, and it will all be great!!
For those of you who will ask, KISS=Keep It Simple Silly/Stupid