My mom died of melanoma at 38. i am trying to prevent. are green tea and vitamin d good for prevention as well as sun protection? is melanoma hereditary?

Yes: There are multiple hereditary conditions that increase risk of melanoma, so yes. Prevention would be best done with routine skin exams as well as avoidance of sun; I do not believe there is enough data on green tea or vitamin d in the setting of melanoma to make a recommendation one way or the other.

There is no herbal: There are no herbal treatments or preventives for melanoma. Avoid the sun. If she/or others in your family have developed cancers early, then there may be a familial incidence.

Sunscreen!: Sunscreen and limiting your exposure to uv radiation is your best way of preventing melanoma. There is not clear evidence that green tea or vit d will decrease you risk. Melanoma is hereditary. In addition having regular skin examinations by your friendly dermatologist is important for those at risk of developing melanoma.