IceKoldKilla,
You ask a very difficult question. As you know, Restoring Hope is a complicated quest with many related side quests (An Ear to the Ground, Return to Sender, Medical Mystery, Tags of Our Fallen, and others). Perhaps not doing something in those other quests could cause the issue you're having. It may be impossible to determine what is causing your problem.
Anyway, you can, to move along, attack Nelson by yourself to finish the quest. I did that once. I used the Rat Slayer to pick off the Legion soldiers there. I situated myself up on the nearby cliffs, staying in a concealed location, but still able to snipe those below. I eliminated all the Legion soldiers by that method. I didn't knock off Dead Sea until later (he's in one of the barracks). Be aware that finishing Restoring Hope in NCR's favor will earn Legion infamy. After that, you can expect to be attacked by Legion assassins. You will have failed the quest We Are Legion.