If she was born before her father got his green card, there is a small possibility of her being eligible to adjust status via 245(i) derivative grandfathering, depending on how and when her father got his green card and when he lost it. Or direct grandfathering if an immigrant petition was directly filed for her before April 30, 2001.
She should find out as much as she can about her father's green card -- who filed a petition for him, when was it filed, when was his green card approved and what was its category, etc. with copies of the related documents if possible (e.g. I-140/I-130 receipt or approval notice, a copy of the green card, etc.). Then arrange a consultation with an immigration lawyer to analyze it to evaluate her eligibility for 245(i). The lawyer may ask for additional details/documents before making a conclusion.
245(i) can get really complicated when it comes to derivative grandfathering, and a second opinion from another lawyer is recommended, especially if the first lawyer isn't confident that it's a clear cut case one way or the other.
Make it clear to each lawyer that you are only seeking a one-time consultation (with a follow-up if it's necessary to obtain additional information) to evaluate her 245(i) derivative grandfathering eligibility, you're not looking to have the lawyer handle the green card case itself. That way they're not tempted to lure you into false hope and take your money for a hopeless case. Then if the lawyer says she's good to go, find another one to actually handle the case after marrying her, or handle it by yourselves.
If she can't qualify through 245(i), it's game over. She'll either have to continue to live in the shadows, facing the possibility of ICE agents arresting her for deportation at any random time, or leave the US and wait out the 10-year ban.