After feasting in the deserted Aramean camp, what did the four men with leprosy decide to do?

Answer: Tell the king's household

They said, "Today is a day of good news," and staying silent would be wrong, so they went to tell the king's household.

“Finally, they said to one another, “We are not doing what is right. Today is a day of good news. If we are silent and wait until morning light, our sin will overtake us. Now, therefore, let us go and tell the king’s household.””— 2 Kings 7:9 (BSB)