"I noticed your grass needs cutting it's going to be a nice day today so it would be a good day to do it"
'Yes it's looking lovely isn't it? We're off out for the day, looking forward to it!'
" your windows really need a clean here is the number of my window cleaner"
'Haha good thing I know you well enough not to take that the wrong way MIL! The windows are fine thanks. If your window cleaner is looking for more clients I can pass this number around though?'
Bat back or ignore, but do it in an off the cuff way - as if her comments are not really very much on your radar. Make the replies kind of dismissive.
This is more of an issue, to me:
I have spoken to my dh about it and he says that he feels like it is a direct attack on her.
Be absolutely bloody crystal clear to your DH - if you want to speak to him about an issue you have, you expect him to listen fairly to you, and to support you as his wife, first and foremost, EVERY TIME. If his default position is 'that's my mum, you can't criticise her' - then - your marriage won't be happy and is less likely to last. End of. It's worth telling him that right now, before children, before anything. What does he want to be? A grown man and a husband, first and foremost? Or a child and a son to his mum? His choice.