Hilchos Nedarim 13:17

Let’s say that a woman made a vow while in her husband’s domain such as prohibiting meat to herself after 30 days or that she will be a nazir after 30 days. Her husband annulled her vow, but then he died or divorced her within that 30-day period. Even though she’s a divorcee or a widow when the vow would take effect, it doesn’t take effect because her husband annulled it.

Hilchos Nedarim 13:18

Let’s say that a widow or a divorcee takes a vow prohibiting wine to herself when she marries. If she gets married, her husband can’t annul that vow. If a married woman vows prohibiting meat to herself when she’s divorced, her husband can annul that vow, with the result that she can eat meat if they divorce.