Keep the Change, You Filthy Animal
The ending to Skyfall is basically Home Alone but with more deaths and explosions. Bond is Macaulay Culkin and Silva is Joe Pesci, except instead of trying to rob the house of valuables, Silva is trying to rob M of her life.
So, yeah, the stakes are a smidge higher.
Luring Silva to Skyfall puts Bond on his home turf. Literally. Skyfall is Bond's family estate, so he knows it like the back of his hand. Plus, way out in the boonies of Scotland, Silva's technological prowess can't help him. Having to match Bond in wits and strength, Silva finds himself at a disadvantage.
Bond's only ally is Kincaid, an elderly gameskeeper, who explains it best, "But if all else fails, sometimes the old ways are the best."
And the old ways work. In the most intense game of Survivor ever, Bond is able to outwit, outplay, and outlast Silva. Unfortunately, M dies from a gunshot wound—not even from Silva. Quite an ignominious way to go after such a dramatic struggle.
But M gives Bond a quantum of solace, if you will, with her final words. She looks at him and says, "I did get one thing right."
When Bond blows up Skyfall, we get the impression that he never cared about his parents, even in death; perhaps he also feels that his own parents never cared about him. But M was always a mother figure to him, and in this moment, he knows he made her proud.
Yet the world—and the Bond franchise—moves on without her. M is replaced, and Bond vows to keep fighting…at least until Daniel Craig is replaced as Bond, too.