In my experience, a little larger is better than a little smaller for several reasons...they're easier for residents to hold onto, they're easier for the nursing and housekeeping staff to see and move if/when necessary, they're harder for other residents to secretly "borrow", and they're easier to launder.
Most residents that I knew kept their dolls/animals very close (in bed with them or tucked tightly in their arms) so you may want to reconsider the 'extras' that you mentioned and just stick with the dolls themselves. Many of the residents are Alzheimers or dementia patients and the details of a sleeping basket and bedding or change of clothes would either confuse them unnecessarily or not be used. Personal space is usually very limited. Checking with the head of nursing will give you a better idea of what would work best and is probably a step you should take before starting production.
Also, don't forget to add some kind of label that can be written on so when, not if, the doll makes it's way to another resident's room, it can find it's way back to the rightful owner without any questions.
Best of luck, it's a great idea and Christmas is a great time to start your donations. The staff at many facilities are always looking for new Christmas ideas.