A spider egg sac without the mother attached would not be that of a wolf spider. Wolf spiders carry the egg sac about attached to the mother’s spinerets, and then, when the spiderlings emerge, they ride around on the mother’s abdomen for a while. I’ve heard several people recount that their most frightening spider encounter was stepping on a large wolf spider to kill it, only to have dozens of tiny wolf spiders flee in every direction from their oozing mother’s corpse — Good stuff for an entomo-horror flick! Anyway, without further description of the egg sac’s shape and size, hard to be sure, but if the sac was flat and satiny looking, perhaps that of a gnaphosid running spider or relative.