In "The Monkey's Paw," why did Mrs. White go "scurrying to the door at the postman's knock"?

The opening conversation in Part II of "The Monkey's Paw" shows that Mrs. White has very little faith, if any, in the powers of the monkey's paw. She seems to think that her husband was foolish to buy the talisman from Sergeant-Major Morris, although her husband never says how much he paid for it.

"I suppose all old soldiers are the same," said Mrs. White. "The idea of our listening to such nonsense! How could wishes be granted in these days? And if they could, how could two hundred pounds hurt you, father?"

From the author's perspective it was necessary for Mr. White to make at least a token payment in order to establish that he was the owner. Only the owner of the paw, according to Morris, can make the three wishes. Although Mrs. White shows her skepticism, this 

...did not prevent her from scurrying to the door at the postman's knock

She is obviously hoping against hope that the postman will be bringing a letter announcing that they have won a prize of two hundred pounds, or something of the sort. She certainly doesn't expect a representative of Maw and Meggins to arrive in person. When the only piece of mail delivered by the postman turns out to be a tailor's bill, she refers 

...somewhat shortly to retired sergeant-majors of bibulous habits when she found that the post brought a tailor's bill

The fact that the mail brought a bill instead of a surprise announcement that they had two hundred pounds coming from some source, Mrs. White is reminded of the household finances. She is resentful of the amount of whiskey the sergeant-major consumed the night before because of the expense. This will remind the reader that both Mr. White and Herbert were drinking more than usual along with their guest. Herbert's accidental death at the textile manufacturing plant could have been caused, somehow or other, by the monkey's paw, or it could have been due to the fact that Herbert stayed up late, drank too much, went to work with a hangover, and was caught up in the machinery because he was less attentive than usual.

"Morris said the things happened so naturally," said' his father, "that you might if you so wished attribute it to coincidence."

The fact that the postman does not bring anything pertaining to an unexpected gift of two hundred pounds is also intended by the author to deceive the reader into believing that the monkey's paw was a fake. This makes the visit by the man from Maw and Meggins that much more ominous and dramatic. The author dramatizes the bad news by having this representative arrive in person. It would be far less effective, for example, to have the postman deliver a letter in a business envelope announcing with deep regret that the White's son had been accidentally killed in a factory accident and the company was presenting the parents with two hundred pounds compensation. The gentleman from Maw and Meggins is obviously the bearer of bad news and is extremely reluctant to do so.

She was watching the mysterious movements of a man outside, who, peering in an undecided fashion at the house, appeared to be trying to make up his mind to enter. In mental connection with the two hundred pounds, she noticed that the stranger was well dressed, and wore a silk hat of glossy newness. Three times he paused at the gate, and then walked on again. The fourth time he stood with his hand upon it, and then with sudden resolution flung it open and walked up the path.