Which detail most belongs to the conclusion of " the monkey's paw"?

Supernatural matters aside, we think the ending also does a lot of character building. When Mrs. White is unable to sleep because she's thinking of Herbert cold and alone, and when she is willing to accept Herbert even mangled and undead, we understand the depth of her love and grief.

What really shows in the ending, though, is Mr. White's love for his wife and the sturdiness of his character. He'll do anything for her – even wish a dead son back to life against his better judgment. His ability to do what he knows is right for his wife – stop the undead Herbert from coming back or comfort his wife in her time of need – shows us how strong he can be. He can put his own grief aside to help his wife deal with hers.

Let's take a look at the final lines of the story:

A cold wind rushed up the staircase, and a long loud wail of disappointment and misery from his wife gave him courage to run down to her side, and then to the gate beyond. The street lamp flickering opposite shone on a quiet and deserted road. (3.49)

Hmm. This suggests that Mr. and Mrs. White both believed it was the undead Herbert at the door. Mrs. White, described as being mentally faster than her husband, will surely put two and two together and realize that Mr. White wished away her Herbert.

Will she forgive him? Will Mrs. White drive herself mad obsessing over the paw, the wishes, and Herbert's death? Will Mr. White be able to help her through it? What will become of this elderly couple now that they are virtually alone in the world?