Evil will leave when a house has no more human unrest to offer or sometimes it leaves on the coat tails of a guest. Evil does like company, something to feed from.
Oh, dear, a mouse in the house saves nine? That is a mixed thought, a warning, really. I think it is actually said that for every mouse you happen to see, there are nine others just like it loose in your house.
A mouse is one of my totem animals by choice. It sits on my left or right with a turtle, my other totem on the other side. I chose these and cannot recall what I must have been thinking.
A long time ago, in another life, in a trailer house with barely one child and an alcoholic borderline mate. Yes, I chose that, too and I don’t know why. Back to complete that thought – I saw a mouse in the bathroom/laundry room. It was small and cute and probably hungry. I put bread out for it.