There are few issues here. If you are one of the heirs who would inherit him if he were to die, you must provide for him and can’t give him your zakat. But if his father is alive or he has a son, then you can give him from zakat.
He has to be poor or needy in order to qualify for being a recipient of zakat.
The zakat must of the previous year be given at once. However, you can give him from the zakat of the next year in installments until its due date.