Molly and Bellatrix

I checked and didn’t see this question already posted, though I may have missed it. But I was rewatching deathly hallows part 2, and got to the fight between Molly Weasley and Bellatrix. I don’t really remember how it went in the book, it’s been too long, but it surprises me that she would even win that battle. Obviously Molly is a very well trained user of magic, but wouldn’t she be rusty after so many years of raising too many kids and generally being the most wonderful person on the planet? It seemed a little too easy, that’s all. Anyone have any input, or share the same thoughts?

Not sure if this is a spoiler, but just in case.

Edit: It also just occurred to me that avada kedavra seems like a pretty nice way to kick the bucket after watching what Molly did to Bellatrix