You did not mention when you were granted asylum. If you were granted asylum short time ago, it is much faster to marry that woman. It will only take you less than a year to get your Green card if you married an american woman. As for your mother, she can apply for a visa and her chance will be higher if she does not mention that you live here! Otherwise, the guys at her consulate will think she will come to america with the intention of overstaying.