Parent has Green card, however need to be aboard for a year or t

My mom has green card, however needs to be home for a year. I understand

I should apply the AP for her. The AP can gurrantee her outside US for

2 years, right?

She can only use AP for one time in her life time, is this right?

 

Is there any other ways to allow her stay out of US for more than 1 or 2 years after the AP?

We are in CA, she is on medi-cal plan. anything else we should be aware of before she leave?

 

How long the AP process will take right now? she plans to go back home in next March.

 

thank you all for help.