Question

why did the boys return the horse.?

Answer.
The boy returned the horse to boy not because they were fraid but because their conscience pricked them.​

Answer 1

The boys returned the horse because they were conscience stricken not because they were afraid as Mourad and Aram belonged to the Garoghlanian tribe which was famous for its honesty. It was their craze for horses which made them steal one. However, after keeping the horse for few months, the farmer John Byro visited their house and saw the horse, he however didnot say anything to the boys rather he praised their family for it's honesty. This is the point where the boys realized that in order to keep their family tradition of honesty alive they would have to return the horse to the rightful owner.