Can we meet my mother in law at the gate she is arriving in Beijing?

My husband and I are arriving from Seattle, USA to Peking at 4:55 pm through Hainan Airlines.
My mother in law who is 84 years old will arrive from the Philippines (through Hong Kong) in Peking at 8:10 pm.
There is nearly 4 hours of difference. She gets anxious easily. After getting our luggage from the baggage area, are we allowed to return to the gate to meet her?
Thank you.