Answer: Yes. Based on the information that you have provided, this student meets the definition of both unaccompanied and homeless, and is therefore eligible for the protections and services of the McKinney-Vento Act.
She meets the definition of unaccompanied (not in the physical custody of a parent or guardian) because the mother had her parental rights terminated and is no longer her legal guardian. 42 USC 11434a(6). Although her mother is a parent biologically, she is no longer a parent legally. The facts that you presented also indicate that the student’s current living situation is not fixed, regular, and adequate, and therefore that she also would meet the definition of homelessness under the McKinney-Vento Act.
Based on this information, the student should be enrolled as an unaccompanied homeless youth, following whatever procedures your school district usually follows to ensure immediate enrollment for unaccompanied youth. We also wonder if her school of origin has been considered. It’s not clear how far she lives from her school of origin, but considering that she is 17, it might be very much in her best interest to remain in the same school, particularly if changing schools could jeopardize her ability to graduate on time, and considering the upheaval she is going through outside of school. We also recommend that the school counselor or social worker check in with the student periodically to see how things are going at home. We don’t know about the student’s mother’s history or present situation, but there is objective reason to monitor the situation.