By the way, why she went to us embassy ? Isn’t she just supposed to buy air ticket and come to us and immigration officers will be the one to allow or not allow her admission? Also what do you mean when say, US embassy allow her to come in? Do they give some documents or put stamp in passport?

If in understand correctly, you can technically apply for new green card, and if USCIS approves it, she can have new green card and come back again.