I don’t see Morgan being part of the Wolves gang. A couple of them tried to kill Morgan and take his stuff, but he used his staff to knock them out and leave them in a car. An episode or two later, Morgan rescued Daryl and Aaron from the trap that the Wolves had set up with the walkers inside of the tractor trailers.
I think the most likely people honking the horn are Ron (older son of Dr. Pete (now deceased) and Jessie), Father Gabriel, or the Wolves gang.
That is a valid point, but I still think it is Morgan. We’ll see.