It is haram to take interest based loan. You must not give your zakah to spend in marriage as zakah shall not be paid by it. However if his daughter is entitled to receive zakah and you give her jewellery from your zakah amount and make her its owner and give it in her complete possession then zakah shall be paid.
Allah (Subhana Wa Ta’ala) knows Best
Darul Uloom Deoband