She can remain in the US while her adjustment application is pending and needs an advance parole travel document to leave the US without abondoning her application. She should have applied for it when filing her adjustment application.
Having entered with a visa means that she can have her status adjusted (i.e. receive her green card) without having to leave the US. If she needs to leave, however, she cannot do it without first applying for and being granted an Advance Parole (an authorization to travel), otherwise her application will be considered abandoned.
[This answer is for general purposes only; it does not constitute advice and does not establish an attorney-client relationship.]
I agree with the answers given, she can wait in the US.
LORIC, Immigration Solutions
Rodrigo Ivan Canido
3333 Bowers Ave, Suite 130
Santa Clara, CA 95054
She can stay in the US while waiting for her adjustment of status application to be adjudicated. There are timing issues to consider. Therefore, work with an immigration attorney to prepare your case.
(626) 771-1078 Los Angeles Attorney Theodore Huang, Esq. This is not legal advice. No attorney/client relationship is established. Attorney Huang is licensed in MD; practice limited to federal law.