All perfect praise be to Allah, The Lord of the Worlds. I testify that there is none worthy of worship except Allah, and that Muhammad is His slave and Messenger.
The wife whose husband died deserves and keeps her full dowry. Allah the Almighty says (what means): {And give to the women whom you marry their Mahr (obligatory bridal-money given by the husband to his wife at the time of marriage) with a good heart.} [Quran 4:4] The property that was given as Mahr (dowry) to this woman must be delivered to her and her ownership of this dowry is not affected by the fact that she married after the death of her first husband. In addition to her entitlement to the full dowry, she has a right in her husband’s inheritance if the husband dies while she is still married to him. Her share of the inheritance is a quarter of the estate if her husband does not have an inheriting descendant, or an eighth if he has an inheriting descendant. Allah the Almighty says (what means): {...And for them [i.e., the wives] is one-fourth if you leave no child. But if you leave a child, then for them is an eighth of what you leave, after any bequest you [may have] made or debt.} [Quran 4:12]
Allah knows best.