Answer:
The nephew
Step-by-step explanation:
The dog's foot prints are overlapping the shoes that are overlapping the tire marks from 3 different tires, if the dog is his seeing dog then it would make sense that the dog's foot prints are next to his and they're going in the same direction, and since the dog's footprints overlap the others it means that they were there last.
People were confused so I'll resay it. The dog is the nephew's seeing dog, so he walks beside him. And if the dog's foot prints are overlapping all of the other's, that means the dog was there after all of the rest of them, and if the nephew is with the dog then the nephew was there last.