That's supposed to be Driver Nephi? The head's in really bad shape, so I can't authorize a full reward. If he really is dead, we're all better off.”— Major Dhatri
After killing Driver Nephi, the Courier can search his corpse and take his mangled head, although if the player kills Driver Nephi without shattering his head, they will instead take Driver Nephi's head. The Courier can deliver either to Major Dhatri for a reward as part of the quest Three-Card Bounty, although they will receive more caps for the latter.
If the Courier does not search the body and take the head immediately after killing him, his corpse will remain where he died to be looted at any point later in the game.