Is giving a sum of money to one's sister to donate as charity with the intention of gifting the reward to one's deceased mother sufficient to fulfill a vow of donating a sacrificed animal during Ramadan for a mother for whom a vow was previously made?

A Muslim should not make vows, but if a vow of obedience is made, it is obligatory to fulfill it. If it is delayed beyond its due time, it is obligatory to make it up along with an expiation for breaking an oath (kaffarat yamin). So, if the questioner vowed to slaughter a sheep in a specific year and distribute it to the poor, which is a vow of obedience, and she did not fulfill it on time, she must fulfill the vow as a make-up and pay an expiation for breaking an oath due to the delay. The expiation for breaking an oath is feeding ten needy persons, or clothing them, or emancipating a slave. If one cannot find any of these, then fasting for three days. Giving charity in money is not sufficient for a vow specifically designated as a sacrifice.