Is it permissible to pay the cost of food for seven orphans after a woman recovers from her illness, knowing that she vowed to feed them but they stopped coming?

Vows of obedience or piety must be fulfilled by consensus, as the Prophet, peace and blessings be upon him, said: "Whoever vows to obey Allah, let him obey Him; and whoever vows to disobey Allah, let him not disobey Him." Making a vow is disliked because the Prophet, peace and blessings be upon him, forbade it, but the prohibition is for disliking, not for prohibition (haram). Fulfillment of the vow should be in the manner it was vowed. So, if you vowed to feed seven unspecified orphans, you should feed seven orphans (breakfast, lunch, and dinner) for the specified number of days, and you can seek help from charitable organizations. If you vowed to feed specific orphans and are permanently unable to feed them after exhausting all means, then you must pay the expiation for breaking an oath (kaffarat yameen). If the inability is temporary, then you should wait until you are able to fulfill your vow and strive to do so. Whoever vows an act of obedience that he cannot perform, or becomes unable to perform after having been able, must pay the expiation for breaking an oath.