In the short story, "The Monkey's Paw," we can safely say that all three major characters have changed to some degree.
Herbert probably goes through the greatest transformation, unwittingly, of course. At first he does not believe at all at the stories of the miraculous power of the monkey's paw. He dismisses it outrightly. He even jokingly says that his father should wish to become an emperor, or at least wish for 200 pounds to pay off the house. His father makes the wish and Herbert dies. And surprisingly on account of his death there is a 200 pounds. Then there is the possibility that Herbert is now alive as a monster as there was a second wish to get him back.
Mrs. Herbert also experiences a transformation. From a happy woman, she is racked with great grief at the loss of her son, Herbert. In the end, she is nearly insane.
Mr. Herbert also changes as he is racked with guilt for his wishes, which he believes has lead to his son's death.
In the end, we can say that there is 180 degree difference in all the characters in the story.