For me, the most frightening part of "The Monkey's Paw" occurs after Mr. White's wife has forced him to wish for their son to return to life. White is very reluctant to do so, but his wife is so emotional and insistent that he finally makes the wish. Then, apparently, nothing happens.
The old man, with an unspeakable sense of relief at the failure of the talisman, crept back to his bed, and a minute or two afterward the old woman came silently and apathetically beside him.
Their bedside candle burns out, and White, holding a lighted match, goes down the stairs to get another candle.
At the foot of the stairs the match went out, and he paused to strike another; and at the same moment a knock, so quiet and stealthy as to be scarcely audible, sounded on the front door.
This single sentence seems like the most frightening moment in the story. White is standing in the pitch-darkness when he hears a quiet and stealthy knock at the front door. We are sure that this is Herbert returned from the grave. Who else would be knocking at their door in that sparsely settled area at that time of night? White has seen Herbert's mangled body and knows how much more horrible he must look after being buried and subject to some decay. Herbert would not exactly be a living man, and he would not be their old Herbert. There would be no more funny jokes. He would be a horrible monster who had come to move back into his old home. The fact that the knock is "so quiet and stealthy as to be scarcely audible" makes the moment seem all the worse. It is as if Herbert knows he looks unspeakably horrible and is timid about signaling his folks to let him in. Mr. White knows it is Herbert but wants to pretend to himself and to his wife that he didn't hear the knock. He doesn't want to open that door and see what he knows he would be facing on his doorstep in the dead of night. We as readers share the father's dread. We don't want to have to look at that horrible monster, and we realize that Mr. White would have no choice but to admit his son if he opened the door. In that case, Herbert would be part of the family again. How could they live with such a creature who was dead and brought back to life and really should be dead and buried? We are not entirely sure--and neither is Mr. White--that Herbert is harmless. Death may have changed his character to match his mangled appearance. He might be more like a vampire or a demon than the old happy-go-lucky Herbert. We can imagine all sorts of things!
The most frightening moment in the story "The Monkey's Paw" may well be the moment when, after the representative of Maw and Meggins speaks to Mr. and Mrs. White and disclaims liability for the accident that has killed their son Herbert, he informs the Whites that they are to receive "a certain sum as compensation," a sum that the Whites fear is one for which they have asked.
... His dry lips shaped the words, "How much?"
"Two hundred pounds," was the answer.
Unconscious of his wife's shriek, the old man smiled faintly, put out his hands like a sightless man, and dropped, a senseless heap, to the floor.
Having learned that their son has been killed at work, Mrs. White's face has blanched, her eyes stare blindly, and her breath is "inaudible" while her husband's face has the look a soldier "might have carried into his first action." They fear that something terrible is going to be said next, something connecting Herbert's death with their actions of the previous night as they recall the sergeant's warning. So, when the representative of the company offers "[T]wo hundred pounds," they know with horror that the first wish made upon the monkey's paw has come true. Because they have not stipulated conditions and sources from which the money may not come, the Whites have inadvertently brought about the death of their son. This fateful knowledge is so horrific that Mrs. White shrieks, and Mr. White, who has made the wish for two hundred pounds, drops, "a senseless heap, to the floor."
For me, the most frightening moment in The Monkey's Paw is when, after the second wish, for Herbert to return from the grave, and Herbert, or some form of him is approaching the house, at the door. Mrs. White is too short to open the top bolt, she is dragging a chair to the door, to let in whatever ghoul or zombie form of Herbert has risen from the grave, while Mr. White frantically searches for the monkey's paw.
He gets the monkey's paw, seconds before Mrs. White is able to get the door open. Mr. White had used his third wish to return his son to the grave where he belongs.
For me, the suspense of reading this part of the story was the most frightening. Wondering what Herbert looked like, after his horrific accident, and that the monkey's paw did not grant wishes in the most positive style, I wasn't sure whether Mr. White or Mrs. White would win this struggle.
Only you can answer this question because only you can say what moment in the story most frightened you. This question is calling for a subjective answer, which simply means it is asking for your opinion. Your teacher wants to know what you think about this story and what part of it scared you the most. If nothing was particularly scary, then your answer can be that you didn't think it didn't scare you; try to give some reason why, like it is too old-fashioned or you could predict what was going to happen, so you were ready for it when the part that was supposed to be scary came.
Subjective questions can be a student's lifesaver: There is no right or wrong answer--unless you leave it blank or go completely off subject. (For instance, don't say that the evil clown scared you when there is no evil clown in the story.)
I hope that helps!