Answer: In the "Monkeys Paw" they never destroy the paw. In the end, after the old lady had wished for her dead son back, her husband realized that if he came back in the state he was after he died (mangled and shredded), then it was better he stayed dead. So he made the last wish (presumably that his son would go back to his grave, they never tell us) and when the old lady opens the door, hoping for her son, no one is there.
