The other posts make good points about possible legal or other complications should her wishes be unclear. Perhaps it'd be easier to sit down with her to talk about that before she moves, under the guise of discussing and making the arrangements for her to move in with you? Provided that's too much for her to deal with in one go, but I can only imagine this is very much on her mind as well.

As to the doctor litespeed mentions, if she dies at home and her doctor isn't available, notify the Notarzt (information 1811 can connect you with the on-duty doctor), who will come by and take care of the paperwork.