Help on a rule

[budjones05]

A runner was rounding second base when she was ran into by or ran into the field umpire. She scrambled safely back into second base. When the ball was dead the crew awarded the runner third base, where they judged she would have been if not for the collision. The offensive coach argued for awarding the runner home as he said he was already waving her in and she would have scored easily. The defense argued she went back to second and that is where she should stay.

Which of the three are right?