I'd go for a whistle, $1 fauxton, trash bags, string and water. Maybe a bandanna and a roll of marker tape.

I figure that if he doesn't already have the stuff then he probably isn't into preparedness and wouldn't know how to use it. I wouldn't bother with a knife or fire-starting, for example, or a compass. If he gets lost a little bit, the whistle should get him found again. If he's lost for days, then he needs water and shelter to survive, and markers to make him more visible to search parties. He may need first aid, but again if he's not trained I wouldn't give him more than a bandanna to bind wounds etc.