Two points in mind

1 - Bathroom door lock
What if senior falls or has a problem, or even panics?
Do you have to break the door?
Get the door lock that you can open with a coin or spoon
(coin: meaning that you use the coin edge to turn the lock open)

2 - Camera
Just like monitoring kid's room, install a few cams around the house where she -God forbid- may get into trouble