In my opinion, she should have just gotten on a plane and returned to the US. She is authorized to board a plane with an expired 10 year card. The worst case would have been to argue her case in immigration court.....or she could have been admitted with NO court appearance. Is her appointment in Lagos? That is the WORST consulate in the world to argue a case, imo. They are tough, and they could easily deny her case. SB-1s are not given easily anywhere. Then what is she going to do?
Good luck. Keep us informed.