What should you do about a sum of money you took from the social security for your deceased grandmother, which the Zakat and Charity Authority refused to accept, after your repentance and desire to return it?

If the amount was deposited into the grandmother's account before her death, or if it was part of her entitlements paid by the state after her death, then it is an inheritance to be divided among the heirs. However, if it was deposited by mistake, it must be returned to the supporting entity. If returning it is not possible, it should be spent on the welfare of Muslims or given to the poor and needy.