Will her B2 visa be revoked with the I-130 approval?

Immigration inspector at the border can deny your mother entry. Every B2 visitor must prove to satisfaction of the Immigration that she/he is entering temporarily and do not intend to stay and become an immigrant. Approval of an I-130 petition is very convincing proof of the opposite: that your mother *does* intend to stay and become an immigrant. After seeing this information on his computer screen, an immigration inspector *must* deny your mother entry unless she can convince him that, even though she is the beneficiary of an I-130 petition, she is not going to file for adjustment of status and become an immigrant *during this visit*, that she intends to return to her country and obtain an immigrant visa through a consular processing there. (Many people are actually doing it: some need to dispose of property or finish other business back home; some have personal circumstances that make immigration to the U.S. right after the approval of I-130 difficult or even impossible). You can expect that the inspector will not just take your mother's word that she intends to return to her country; she will need some pretty solid evidence to back her story. You might want to speak with an immigration attorney so he/she would be ready to act if your mother's entry would be denied.