This is a great question and one that is not answered specifically within the text of the novel. Boo certainly knows his way back home, and he doesn't need anyone to show him the way; after all, he probably has prowled around the neighborhood at night--one of the few accusations about him that may actually be true. He was obviously keeping watch on Jem and Scout on that fateful Halloween night and probably many other nights as well. But when he whispers to Scout to take him back home, it is probably because he desires one last moment alone with his young friend who has so longingly hoped to one day see Boo in the flesh. Boo probably does not know about Scout's fantasies, but Boo may have had a few of his own: He, too, may have wished to meet the children and actually experience a moment of physical contact with them. He willingly pats Jem's head when he is offered the chance, and Boo appears comfortable while sharing the porch swing with Scout. Boo may recognize that his job as protector of the children is over with the death of Bob Ewell, and he may simply wish to enjoy a few last minutes alone with his little friend. Scout never sees Boo again, and Boo must have resigned himself to returning to his exile within the Radley house, where he is immune to the gossip and innuendo that awaits him on the streets of Maycomb.