Does God answer the prayer of the deceased mentioned in the Hadith: "O Allah, do not let them die until You guide them as You have guided us," by causing their loved ones to die in obedience to Him?

The Hadith mentioned in the question has been weakened by many scholars, and Al-Albani - may Allah have mercy on him - retracted his weakening of it and authenticated it. Whether Allah answers the prayers for the deceased or not is among the unseen matters, about which nothing can be said except what has been revealed in the texts of revelation. It is not permissible for a Muslim to ask the dead or the occupants of graves for supplication, as this is a means leading to polytheism. None of the Salaf did so, because it is a means to associating partners with them and worshipping them instead of Allah Almighty. Asking the dead after death does not affect the supplicant's request.