Yes, it is definitely possible. This type of gate pass is obtained from the airline at the check-in counter and it is entirely up to the airline's discretion on whether to provide it. Ask really nicely.....
As a back-up plan, you could (a) purchase a refundable ticket for a flight that departs some hours after your mom's flight departs so that you can go through the checkpoint with her and then cancel the ticket before boarding. Make sure your flight is scheduled from the same terminal as your mom's flight or that it is possible to travel airside between the terminals; (b) if you have access privileges to an airline club then ask the club to provide a pass so you can visit someone at the club.