Reverse the call and place runners on the bases they would have reached in the umpires judgement.
Just what this crew did.
But they didn't do this. They called Foul ball and further added to the nonsense by saying let it go. The runner scored as a result of them giving the defense 2 reasons to not go after it. It's possible they ruled that she would have scored anyways, but the OP stated he thought 2B or maybe a 3B. One of them seems like the equitable solution without me being there.