Thanks for the replies
@Sarasa @annielou @Woo2
I am indeed glad he didn't come to any harm. I don't know why he went to the other home but maybe it looked like the his one!
As he may get up at any time, they are checking on him once an hour every hour during the night and trying to ensure there is someone around the lobby/dining area early in the morning - but they have to hope no one tries to get up on their own and falls over, or something else... I expect they will also at the very least change the door code.
@annielou apparently dad has a loop going on his car, so it's not just your mum. Dad has to find his car, get rid of his car, etc... and now his wife - meet up with, find or whatever.