Is it permissible to give Zakat on wealth or a perpetual charity on behalf of the deceased from the inheritors' money to pay off his debts or to earn reward for him in his grave?

Zakat is obligatory on the debts and assets of the deceased that were due before their death. It must be paid from the estate before its distribution, even if the deceased did not make a will concerning it. The zakat should be disbursed to its eight categories of recipients mentioned in the Quran. It is permissible to give an ongoing charity (sadaqah jariyah) on behalf of the deceased from the debts or the estate after paying zakat, provided there is an agreement among the adult, sane heirs. However, for a minor or a person of unsound mind, their share must be disbursed before any charity is given. Giving charity on behalf of the deceased, especially ongoing charity, is among the best things a living person can do for their deceased loved one.