Reply

Your mother can travel using her expired green card and the I-90 Receipt Notice which indicates the green card extension. But sh needs to return to US before the extension expiration date on the Notice.

If the green card extension date on the Notice will expire very soon or has expired before she leaves US, she may call USCIS to make an appointment with USCIS Field Office in your area to get the green card stamp on her passport. This green card stamp is valid for one year and she can use this green card stamp to travel.