woojr,
we only hear your side of the story.
And the story you 've told is of a delightfully, independent woman who simply isn't handicapped by what other's think she can't do.
There may be more. She may be treacherously and manipulative, but you haven't told that story. The "power struggle" you describe is about your caring and worry for her. And her vitality and success in maintaining the things that keep her happy.
Even when you say that she crawled through the snow up to her front door. Rather amusingly , you add the comments about yourself--falling in that same snow.
You say that she goes to the wrong door and then proceed to say that the delivery person was placing the packages at the side door. So really the delivery person is placing the packages at the wrong door.
You don't leave these details untold.

You don't brag about the myriad ways you and your wife help your mom. It is impossible to repay our moms even small portion of what they have done for us.
I see healthy dynamict in your posts. Though I hope your mom never falls under your desired restrictions, I also hope (and think) you are predominant in the will she won't show you.
Ha, ha, you tell her to arrange her own funeral.
Cheers and blessings to all three of you.