How can I stop my mother-in-law from always telling me how to raise the children?

My husband always take her side.

This is a problem of asserting yourself with both your mother-in-law and your husband. You should try to your husband’s mother that, although you love and respect
her, you uncomfortable about her giving you advice about the children, and you would prefer to learn by your own mistakes. I also recommend your being assertive with your husband and letting him know how his behavior in this matter is making you feel. Tell that he doesn’t necessarily have to side with you, but that you would appreciate it if he would allow you to work out the relationship with your mother-in-law without his interference.