My heart goes out to you.
Everything I've read and heard about meth addiction is that it's very tough to beat. But it IS possible.
Hepatitis C is another tough one... but treatable. I have a family member currently clean from drugs (including meth) after many years of abuse who is being treated for Hep C. The treatment is pretty rough ~ making the person quite sick, but their doc is working with them to figure out a tolerable and effective treatment plan.
I don't know what the "trigger" is for a person to turn their life around and fight to overcome drug addiction. I had to go no contact with my relative for my own sanity, and despaired of them ever finding a rock bottom or pulling out of the crazy whirlwind of self-destruction. The person was (still is) quite young with great potential... and lost pretty much everything during the bad years.