Is a housewife's feeling of a hair falling between her eyes and the appearance of a guest afterward considered an ill omen or a good assumption about Allah?

The falling of a hair or sensing it between the eyes has no effect on the arrival of a guest or anything else. Believing in such matters is baseless and may fall under minor polytheism (shirk (definition) asghar), because Allah has not made them causes. This differs from optimism through good words, which the Prophet, peace and blessings be upon him, encouraged. Whoever believes that a twitch of the eye, an itchy hand, or a falling hair has an effect, has fallen into the blameworthy superstition (tīrah) according to Islamic law. Such a person must seek forgiveness, repel these whispers, and say: "O Allah, there is no good except Your good, and no omen except Your omen, and there is no god besides You."