What should one do with the money of a vow if he vowed to give it to a needy woman but could not find her at the time of payment?

Vows must be fulfilled once their destination is specified, and it is not permissible to deviate from it. It is also obligatory to deliver it at its appointed time, and it is permissible to deliver it before its time, just as Zakat (definition) may be advanced. If it is impossible to reach the specified destination, the vow must be given to another party that possesses the same characteristics intended by the one who made the vow.