What is the Sharia ruling regarding a wife whose husband is absent for long periods, and she has a strong sexual desire and cannot control herself? Is it permissible for her to masturbate or not, and what is your guidance for her?

If the husband is able to travel with his wife to his workplace, that is preferable. Otherwise, she must be patient and chaste. She can be aided in this by fasting, lowering her gaze, closing the doors to temptation, staying away from things that arouse desire, strengthening her connection with Allah, seeking refuge in Him, relying on Him, accompanying righteous women, occupying her time with beneficial deeds, and persistent supplication while having a good opinion of Allah.