What is the ruling on one who vowed to pray two rak'ahs after 'Isha throughout her life to be delivered from a difficult situation, but fears she may not be able to fulfill her vow due to menstruation?

The making of vows (nadhr) is disliked (makrooh) and brings no good, due to the Prophet's (peace be upon him) prohibition of it. However, it does not change anything from divine decree. Rather, "it is extracted thereby from the miserly." Despite its being disliked, vows of obedience must be fulfilled, by the consensus of scholars. And whoever has vowed to pray two rak'ahs after 'Isha' throughout her life must fulfill it, and the time of menstruation is not included in this. If she misses the prayer on a particular night, she must make it up along with an expiation for breaking an oath (kaffarat yameen). The feeling of guilt while performing the prayer is unjustified, because fulfilling a vow is an act of closeness to Allah Almighty.