请问8 老师

This is for my friend.

Her mother stayed here for 2 years to help her take care of her baby. Her mother did not plan to come back anymore and so did not do extension. Her mother came back to China ~1 year ago, and my friend wants her mother to come back for another half a year or so. Can her mother still get visa approved? Or her mother has to wait until staying 2 years in China?

Many thanks.