My mom is the same way. She insisted on coming to stay with us for 7 weeks after the baby was born. OMG. The first week she was helpful but after that it seemed like she wanted to take over.That won't happen again. :)
I simply tell her each time she goes overboard that I have to learn to do this on my own. Everything isn't always gong to be smooth and perfect but I am learning to do this and I need her to relax and let me.
This usually works. Good Luck!