If my father dies before my step-mother and then she passes what am I entitled to since they have no will? My step-mom has been married to Dad for 30 years. She has no children and I am his only child. I was raised in their home. If she has no will does this really mean her relatives will receive everything my family has? And I will receive nothing?

It is good for us to know which state has jurisdiction over the case.

... If she has no will does this really mean her relatives will receive everything my family has? And I will receive nothing?

As GV70 suggests, the answer depends on where you are.

But in general, no, the intestacy statute would normally give a portion to the decedent's issue and a portion to his widow.

In general in most areas with the limited info given, no you will not receive anything, thus the reason there needs to be wills. Or accounts as co owners and the such

As has been said, it depends on the State.