Offer to Purchase Oil and Gas Interests

I had made a post back in April not knowing much, but a reply to my post help a lot and I have been doing some digging for more information. I found out my great-great grandmother passed down these mineral rights of 51.12500 acres and I think just about everyone in my family has been signing them away. It’s approx. 0.79883 net acres. I have looked up the deed but really don’t fully understand how that comes down to my mother legally? I guess my question is, are there papers that we should have showing these rights? It’s sad we never knew anything about this until Antero came to us and I was thinking it was a scam. It may not be a lot of net acres, but we refuse to sell it and I’m not sure if I need to send this letter back stating that? Just so many questions.