If I were you I'd get away from these parents. I'd also get into good therapy that wasn't at all connected to TM.

The thing about TM and other related meditations, often it can make a person spaced out, so it isn't necessarily a cure all or for everyone all the time.

I hope you are in or get into good solid safe therapy. For you, not for anyone else. I suggest not worrying now about whether you can or can not stand up to your mother, I personally think you need to get away from her and get into therapy.

Eccentric or not, your parents offering sex is not okay. Not healthy.