Is it permissible to offer the monetary value of a vow to the mosque instead of fulfilling it by slaughtering, especially since the questioner vowed to offer food to the mosque (a large bowl of food), but is unsure whether she vowed to slaughter an animal, and wishes to fulfill the vow at her brother's wedding?

Whoever vows obedience must fulfill it, for the Prophet, peace and blessings be upon him, said: "Whoever vows to obey Allah, let him obey Him." You must provide food for the worshippers in the mosque for them to eat, and it is not permissible to offer it at your brother's wedding. As for slaughtering the sheep, if you remember that you vowed it, then you must fulfill that; otherwise, no.