Mothers have a way of doing this. Luckily, hair isn't my mother's issue...but she has her own issues. Uggh!
I agree with Jillipoo's assessment that this is more about your mother's cognitive distortions. Try not to take it personally. I also agree that humor is a good way of dealing with the situation.
When my mother kept giving me advice, I told her "that from now on, when you give me advice, I'm going to tell you "Thanks mom, I will give that some thought" but then I will do whatever I want." She and I laughed, but that's exactly what I do now. Sometimes my mom gives good advice and I take it, but at other times, I just listen to it and that's the end of it. Being direct with her, although it came across funny at the time, I think it helped my mom know that it's okay to talk to me about issues but ultimately I make the decision about my own life. She still nags at my brothers, but she really doesn't nag at me anymore.
That's right, I said it! I wear scrunchies!!

I am a sulfate washing, cone slabbing, curly lovin' s.o.b. The CG police haven't caught me yet.