She has options to fight the the cancellation of her green card. A lot will depend on her intentions at the time she left, and if she has ever returned during the 5 years outside of the US. Generally speaking, if a LPR (green card holder) has left the United States for longer that 1 year (without advance parole) the presumption is that they intended to abondon their LPR status. But, the burden is on the government to prove her intentions. If you are able you should hire an attorney as soon as possible.
Answered on Feb 13th, 2017 at 8:59 PM