What should a woman do who vowed to give a gold ring to another woman who has since died; should she give the ring to her daughter or donate it as charity?

If the vow is made to a specific person, and the intention behind it is to seek nearness to Allah and to give charity, then it becomes binding for that specific person. If that person dies, it becomes part of their inheritance and is considered a portion of their estate. However, if the vow is in the nature of a gift or a donation, then the one who made the vow has the right to dispose of it as they wish.