As Morris warns the Whites in the beginning of the story, use of the Monkey's Paw brings with it tragedy. These warnings certainly are fulfilled, as that initial wish destroys their family.
As this story opens, the Whites seem to be a happy and functional family unit. But when Mr. White makes the first wish for the two hundred pounds, that happiness will be shattered. Later the next day, they will receive the two hundred pounds they had wished for as compensation for the death of their son, who had been killed at work.
This news has a deleterious effect on the two parents. Both are grieving, but in her grief, Mrs. White fixates on the Monkey's Paw in the hopes that it will bring her son back. Thus, she demands that they use it again—this time to revive the son they had lost.
There is a desperation and intensity at this point of the story as the wife pressures her husband into acceding to her wishes. Later, when they hear knocking at the door, it seems as if the wish has been fulfilled.
At this point, the wife is driven by an intense hope and fervor at the thought of having her son returned to her, while her husband is concerned with the thought of just what kind of cruel turn that second wish might have taken. Thus, he uses the final wish, undoing the effect of his second.