I would, quite possibly, have felt like you with my dc1. There were so many things that my mum did (and FIL too, for that matter, but not MIL) that really annoyed me. I, too, saw it as deliberate assertion of her mothering skills and ideals over mine.
Then I had dc2 and I learned to unclench a bit. Yes, routines need structure and LOs thrive on them. No, routines do not need to be set in stone. LOs can cope with some variation. And,y'know what? You yourself will probably muck up the routines, too, soon enough. Dc2 changes everything!
If your mum craves more time with her dgc, why not let her have it? Now that I live 30-something miles away from my parents I bitterly regret not having taken advantage of them when I lived 1/2mile away from them. But, no, I was fiercely - stupidly! - independent.
One thing you might like to do is to get your mum to put dd to bed after a wired evening, so that she can understand the issue and not just see it as her dd trying to boss her around. It worked for me: no matter what I said, mum would not stop doing things like giving dc1 chocolates or presents just as we were leaving their house at 5pm. It was not until she tried to give him supper and put him to bed after having given him chocs at 5pm, that she understood what I was on about and stopped. She still does it occasionally, but I have learned to judge when it matters (and she respects that) and when it doesn't (and she respects that, too).
My mum has a fridge magnet that I used to hate, but now accept and understand -
Grandma's House: Children Spoilt To Order