Hello.

My mom has a green card but she left usa last year . She is coming back in April .

Q... you thing she is going to have a problem coming back?

If she was gone more than 1 calendar year she may have automatically forfeited the green card. Contact US immigration asap to inform them she plans on returning

United States Permanent Resident Card - Wikipedia, the free encyclopedia (http://en.wikipedia.org/wiki/United_States_Permanent_Resident_Card)