Was at DD's H.S. game; we had a runner at 2nd, batter hit a line drive down 3rd base line "Fair" ball rolls past the H.R. fence, Blue picks up both hands and yells dead ball, awards the batter 2nd base and the runner (who was on 2nd was clearly half ways to home) had to go back to 3rd. Blue said she had to be pushed in.
What rule would apply on a ground rule double with a runner at 2nd ?