You are in a difficult situation here godfreygirl, you obviously don't enjoy their visits at the moment, with the way they behave, but you don't want their visits to stop.
If it was me, I woud get a simple hook put high up on the bedroom door, when they try to go in, say, ' You can't go in there, Nanas tablets are in there, come and play in the living room' Its a reasonable request and just looking after the childrens safety.
Whatever they normally go for in your fridge, bisuits, chocolate, cheese, etc, make sure they are 'not there' if you know they are coming to visit.
If they want to run around the corridors, tell them, 'you cant run around out there, some of the old ladies here are poorly and need to sleep'.
Do you have things in yours to keep them interested?
Children these days seem to think that you need computers to have fun, sit them down and teach them some card games,
My grandsons love rummy, domino's and ludo. X