Having been married quite a while now, I have a little advice I would like to share on the subject of mother-in-laws:
1) Don't say what you are thinking, unless you are being directly trampled on, in which case, keep a level head and try to stand up for yourself without giving the other party ammunition or reason to make the situation any worse.
2) Keep your distance. Preferably over a thousand kilometers and over multiple state lines.
3) The longer you can leave having kids, the longer they will keep their distance.
4) I'm also planning on spending time teaching my kids how to dress up as little punks and act like they have attitude around grandma ("Barbie is a misogynist symbol of a repressive, capitalist society, Nanna!"), in order to score new clothes and brownie points from Mum.
*sigh* I can only dream. ;)