Filing a case alone for an annulment (or any case) doesn't mean asking party would definitely get what s/he is asking for; rather everything must need to be proven in a court of law. Plus, obtaining an annulment is VERY hard/tough unless there is a compelling reason existed, i.e. one of the parties was underage at the time when marriage occurred or was married before (not divorced), or lied about having serious disease, or did not disclose about not having intention to have children with new spouse, etc.
As for annulling the marriage based upon immigration fraud (as asking party usually claims that respondent defrauded him/her to gain immigration benefit), then it is VERY hard to prove, almost none to zero, unless there is something in writing about admitting this fact by the respondent. Plus, family court judges normally DO NOT annul the marriage even if there are satisfactory evidences to do that. Because they know that alien-respondent would get deported if they would annul the marriage. They are normally very sympathetic to aliens. So, the chances are- a marriage won't get annulled even if a party would wish for it so desperately.
However, there are always some judges who are biased. Thus, it could be possible that judge might annul the marriage. If that would happen in this case, then she should try her best not let her marriage be annulled. Thus, she must need to research and study similar cases in her state which is easily to find in Law Library or online. And if her marriage does get annulled, then she must need to appeal the decision of lower court in the higher court; otherwise she would get deported in the future.
Read one of my postings here-
http://immigrationportal.com/showthread.php?t=209284
Just you to know, I practiced immigration, matrimonial (NJ laws) and Bankruptcy laws very aggressively. And I started my career by handling VAWA cases for State sponsored advocacy agency.
Good luck.