You and your brother are going to have to sit your father down and have a serious talk with him - tell him it's not only our mum who is at risk, but he and other people could be in danger from her. She might switch a gas thing on without lighting it - or cut herself, fall downstair or even in the garden or go wandering off into the road and get knocked down. And you don't need the worry of 4.30am phone calls becaue she's lost all concept of time. If he is adament about not getting help, ask him to let you at least talk to the doctor to see if anything can be done - warn him a fall or anything and the whole thing could be taken out of his hands, like it or not.