
Prior to filing for U.S. Citizenship, she would have to apply for a green card and become a permanent resident. Since, her marriage is probably not valid under U.S. law, she would have to apply for permanent residence another way (ex: through employment, diversity visa, etc.).
As far as if she is living in danger, she can apply for refugee status, and then for asylum. If she can become an asylee, she can later apply for permanent residence.