Maybe this woman is a lot kinder than I am but I'm an old cynic. As you say jen4jenuk2000, your dad doesn't seem to be getting anything from these visits and I doubt that this woman is either (sorry ) so something else has to be going on.
I had a very illuminating chat with the manager of the care home my aunt's in because of a potential problem we were having with a distant relative who suddenly took an interest (only short lived as the aunt wasn't actually on her death bed so any inheritances have to wait for now... ), and she said that from time to time they do find a resident with a relative pushing a pen into their hand and paperwork ready to sign, so that kind of thing does go on. I'm not saying this is the case here but you never know!
Our situation was handled very well. The distant relative was going to be told by the staff that the aunt was too ill for visitors she really didn't know, but, like I said, I don't think we'll be seeing this particular cousin until the reading of the will anyway.