Does giving the vowed amount to one's needy father count as fulfilling the vow?

A conditional vow must be fulfilled if the condition is met. If your father is in need, he is among the needy recipients of the five hundred [currency units], but it is not permissible for him to take it all for himself. This is because the intention specifies the beneficiaries of the vow, and intention is significant in actions. If you are obligated to support your father, then by your support, he is no longer considered needy, and thus not among those who are in need.