Yeah - my guess is dog. Coyotes are generally the size of a medium dog...and I would bet money they would check out the coop before coming to your back door.
I'd guess you are right. If your son saw the neighbor's dog that's probably what it was. Plus KKatknap had a very good point, if it was a coyote or a wolf, it most likely would have headed to the coop first. It sounds more like dog behavior to go to your back door (looking for handouts) instead.
If the kids think it was as big as or bigger than the malamute, it was a dog. Coyotes are pretty small, usually 20-40 pounds. Coyotes can get really bold though, we've had them come right up to the porch. A wolf would not likely come that close to anything smelling like people unless it was already used to people, and they don't normally travel alone either.
Those look like dog tracks to me. To be honest though, as far as your kids go, a lot more people are killed/mauled/bitten by dogs than coyotes so I would be more worried if it was a strange dog.