What is the "rising action" in "The Monkey's Paw"?

Rising action takes place between exposition (setting up the characters, setting, and situation of a story) and the climax (the point of highest dramatic tension). The rising action is all about building to the climax and how the conflict escalates to the final confrontation.
In "The Monkey's Paw," the rising action occurs when Mr. White ignores the sergeant-major's warnings about the monkey's paw and makes a wish on it anyway. This generates suspense, leaving the reader to wonder if the sergeant-major's warnings are legitimate and if horrible things will befall the family after Mr. White wishes for two hundred pounds.
When Herbert is killed at work and the Whites receive two hundred pounds as recompense, the tension escalates. Mrs. White goads her husband into wishing their son to return to life, setting the stage for the climax where this does appear to happen.

The rising action of a story is the way that the plot is established and developed, and the events of the rising action lead up to the story's climax. The plot of "The Monkey's Paw" is established with the arrival of the White family's old friend Seargent-Major Morris. He tells the family stories of his time abroad and eventually begins to talk about the monkey's paw that he says grants wishes—but only at a severe price—which was meant to teach people about the necessity of fate.
The family demands to see the paw, and Mr. White eventually takes it and pays Morris for it, despite Morris's protests. The family confers on what to wish for and settles on Herbert's plan to wish for the money they needed to pay off their house. The next day, Herbert dies at work, and the family receives the exact sum they asked for in the form of Herbert's life insurance. Mr. and Mrs. White are distraught and discuss bringing Herbert back with their remaining wishes, which they finally attempt.
All of these events and any other plot details contained between the first events of the story and the climax (the arrival of the unseen, late-night visitor) listed here can be considered rising actions.

Rising action can be defined as those events in a story that build suspense and increase the readers' interest. In "The Monkey's Paw" the rising action starts when Sergeant-Major Morris tells the Whites about the paw and how the fakir put a spell on it to grant three wishes. He further tells them that if those wishes are granted then unpleasant consequences will follow. This is what happens to those who defy the power of fate. Morris speaks from personal experience here, and as he doesn't want the Whites to succumb to the temptation of making three wishes on the paw, he throws it into the fire.
Yet, Mr. White retrieves the paw from the fire. This takes the rising action to the next level. Treating the monkey's paw as a harmless piece of mumbo-jumbo, the Whites proceed to make their first wish: to have the £200 they need to pay off their mortgage. Their wish is duly granted, but not in the way that they'd hoped. For their sudden windfall comes in the form of compensation paid out after their son Herbert dies in a workplace accident. At this point in the story, the suspense is building; we're anxious to know what happens next.
The next and final stage of the rising action comes when the Whites use the second of their three wishes to try and bring Herbert back from the dead. This will lead directly to the story's creepy climax.