It won't show up,it's a bug.You can't finish the quest this way,you need to go near mariposa military base and travel around it until you get an encounter.There you will find some dead bodies one of which will contain a super stimpak now you need to look around and find a guy lying on the ground.Talk to him and then use the super stimpak on him.After the leave the encounter and you can go back to any BoS bunker (ecept Lost Hills) and recieve the reward.