There was another knock, and another. the old woman with a sudden wrench broke free and ran from the room. Her husband followed to the landing, and called after her appealingly as she hurried downstairs. He heard the chain rattle back and the bottom bolt drawn slowly and stiffly from the socket."
The story ends before the resolution is found but we can infer that Mr. White wishes his son to go away and go back dead because right before the story ended he is scared for his wife to open the door and he has the monkeys paw in his hand and is on the floor scared so you can infer that he wants his son to go away
I think the theme is be careful of what you wish for because when he wished for 200 pounds he got it but it was money from his son who died the next day "well, wish for two hundred pounds, then; that'll just do it."