How is your Dad disabled? Does he use a walker? Young kittys have a tendency to wind around your legs. Maybe an older cat that wil just like to sit and be pette and just keep him company. Will the cat be an inside/outside cat. Maybe a kitty door in place of a litter box. Can your Dad open a can of food or would a box of dry food be easier? Some things to consider. It would be nice if he can do something for the pet. Maybe an older cat that still likes to play with toys ( so your Dad can watch and enjoy) but one that will sit and listen to stories of days gone by.
Wish you luck in finding the right pet. Please keep us posted.