Auntie Snooper Nosey Busybody and Mum's Advice....Is it right?

It is unlikely that your aunt has OCD, OCD is not what causes people to buzz abound the business of others. If it bothers you then tell your aunt in a nice & respectful way that you don't want her advice. You will come off looking better in the end. Your mom is kinda right, people are gonna do what they are gonna do, but you should not enable the behavior, especially if it irritates you. Think about it like this, if your aunt was taking drugs would you buy them for her? So no don't turn up the music for the mad man. When she starts with her advise, tell her nicely that you would prefer not to talk about it and if she does not stop then leave the room. she will get the message over time, if not, you've still removed yourself from the situation.