How I would have saved everyone easily...*spoilers maybe!*
Eben should have taken the generator, the gas can, and the UV light and put it in the basement or a room that the remaining humans could take refuge in and stand their ground.
He could protect the generator while zapping any vampires that came near them, and then just waited until the sun came back.
Heck, they could drive down the street with the generator and UV light as a weapon and go anywhere they wanted.