From my experience:
Gently let your husband know that if his mom says something negative that he should not pass it along to you. What his mom said did not hurt you until he told you. That's how I taught my kid not to spread gossip.
As for your mother in law, if she comments that something is messy, hand her a broom. That's how I got my certified-clean-freak mom to stop making comments. "Vacuum's in the closet" was another one, but she was my mom, not my MIL, so it wasn't as hard for me. Sooo...have your husband do it. :)
Not every state. This is Texas. I'm in California and my kid went to school with shoulder length hair that was half blue. My relatives in Texas kept asking what the school was doing about it. There's nothing on the books about hair and the principal said it looked cool. Hair has always been a control issue in bible thumping communities, which I thankfully am no longer around.