What To Do If Vowed to Give Someone Money, but he Refused to Take it?

The brother has two questions - he says in the first that he was hospitalized and wasn’t able to take care of himself. He requested from the group of people with him that one of them stays with him, but they excused themselves. He vowed to give anyone who stays with him 100 riyals. One of them stayed with him, and, after that, when he wanted to give the one who stayed 100 riyals, he refused to take it. The questioner now asks, “what is obligatory upon me?”