Want my mom's vinyl records from the 1970s  

Actually, there is plenty of vinyl around, and new releases are issued all the time.

You can always just go kick his a$$ and take them.

I probably would.

You can still buy them. Go to record shops, or internet or even a second hand record shop will have them.

These records probably have a close to unique sound, as I have experience with different sounds. Allow me to explain:I first heard Black Sabbath as a bad quality 120 kb/s from a youtube recording someone gave me. I still loved them, but then a friend gifted me their (probably remastered) cds and I love that sound too. I do not know what a record from the 70s would sound like compared to those two and if I were you I would go get them instead of buying new ones. Their sound can not be replicated because they have different indents because of frequency of use by record players and they're your moms so thats a plus too.

By all honesty, the only thing that seems fair to me is that if your mother is done with her LPs, then if both yourself and your brother are intersted in them, you should both have the opportunity to have some of them. I wonder if it would be possible for her to be able to split them in half so that each of you would be able to have some of them. Or would this though cause too many hard feelings between yourself and your brother.