she is not even required to show her green card
Go to this USCIS site and print it out and take to employer
https://www.uscis.gov/i-9-central/employee-rights-and-resources/employee-rights#:~:text=Your%20employer%20must%3A&text=Allow%20you%20the%20choice%20of,Nationality%20Act's%20anti%2Ddiscrimination%20provision.
Your employer may not:
Ask for specific documents because of your national origin, ethnicity, immigration or citizenship status, race, color, religion, age, gender, disability, or genetic information, or because of any other protected characteristic. For example, your employer may not:
Ask for a document issued by the Department of Homeland Security because you are not a U.S. citizen.
Ask for a U.S. passport to prove you are a U.S. citizen.
Refuse to accept your document or refuse to hire you because of an unfounded suspicion that your documentation is fraudulent. For example, your employer may not refuse to accept your identification and unrestricted Social Security card because you have limited English proficiency.
Treat you differently than other applicants because you have, or your employer believes you have, a particular citizenship or immigration status.
Ask to see documents showing your permission to work before hiring you, or before you complete Section 1 of Form I-9.
Refuse to accept your document or refuse to hire you because your document expires in the future.