Is a wife's kissing her husband's hand every morning out of obedience forbidden, and if permissible, who are those whose hands may be kissed?

Kissing the hand has been confirmed in authentic hadiths to have been done for the Messenger of Allah, peace and blessings be upon him. It is permissible or even recommended if the person for whom it is done is a person of knowledge, righteousness, honor, and religious matters. It is strongly disliked if it is done for their wealth, power, or worldly prestige. This ruling is general for men and women concerning their mahrams. As for a wife kissing her husband's hand for the purpose mentioned in the question, there is no evidence that commands it or forbids it, and it is more prudent to abstain from it.