What was Mrs.White's opinion about the monkey's paw and its powers? How and when does her opinion change?

When Sergeant-Major Morris initially explains to the White family that the ominous monkey's paw has magical powers, Mrs. White dismisses the novelty as ridiculous and says,

Sounds like the Arabian Nights...Don't you think you might wish for four pairs of hands for me?

Mrs. White does not believe in its powers and makes a humorous comment to her husband about wishing upon the talisman. Tragically, Mr. White wishes for two hundred pounds, and Herbert dies in a work accident the next day. In part two, Mr. and Mrs. White receive news that Herbert has died and learn that they will be given two hundred pounds as compensation for his tragic accident.
In part three, Mrs. White recalls her husband's wish for two hundred pounds and experiences a transformation regarding her belief in the magic monkey's paw. Mrs. White believes that the magic monkey's paw actually works after she connects the wish to the reward following Herbert's death. She then demands that her husband wish for Herbert to come back to life. Despite the fact that Herbert has been dead for ten days, Mrs. White instructs her husband to wish him back to life, which is exactly what he does. Fortunately, Mr. White manages to make the third wish, for his son to return to the grave, before his wife can open the door to see her son's corpse.