Is it obligatory to spend on a father with a moderate income, and is it permissible to give him from Zakat al-Mal?

Your father is either wealthy with the money he possesses, in which case his maintenance is not obligatory upon you, but it is proper to deliver money to him. Some scholars have held that the father has a right to his son's money, even if he is not in need, provided that it does not harm the son, or take what he needs, or take it to give to another.

Or, what he has is not sufficient for him, and you are well-off, in which case it is obligatory for you to give him what suffices him. The people of knowledge have unanimously agreed on the obligation of maintaining poor parents by their children.

As for giving zakat to the father, it is not permissible if his maintenance is obligatory upon you. If it is not obligatory, then there is a difference of opinion regarding the permissibility of giving zakat to him.