What Happens at the End of The Dead and the Gone by Susan Beth Pfeffer?

On Alex's birthday, Bri goes to the church to light a candle for him. She takes the elevator up from the basement where she leaves a note for her parents. The electricity goes out while she is in the elevator.A couple of days later, Alex and Julie search for her and find her dead, decaying in the elevator. Alex gets himself and Julie a new place to live, but we do not know where.