What stage is my sister in? how much longer will she be gone?

my sister was brought to the united states at the age of 6. she had no choice. fast forward, she married an american last year. this year she began the process of becoming an american. a few months ago she was deported to mexico, last i was informed, her husband wrote a personal letter asking (congress?) (his lawyers?) (the immigration offices?) to bring back his wife, he also included a letter from a therapist/psychologist that confirms he hasnt been doing too well since my sister has been gone. i would like to know exactly what stage she is in? when the process started their lawyers told her it could take a few months or a few years. help.