my mom is 68 y/o and she doesn't work anymore she has her green card and the social security card . she is being in the us for 6 years , but she usually lives the country for a few months and comeback to the us to see my dad and stays for another 6 months or so . she tends to do that often . now how a life insurance plan would work on her ???

If she has a green card and legal, it would work just as though she never left the states.