You probably would have to be acting as intermediary, communicating between U/L and your mom. Perhaps notify driver that the pick up is for your mom, and advise driver what is her outfit or code needed. To your mom, let her know what type of car, license # and driver name. Make sure to tell her that once she is out, to go to the designated ride share pick up. Some airport have a separate area for rideshare, taxi and regular passenger pick up. Last thing you want is she goes to the wrong area, and driver will be looking for her on the designated rideshare area.