The Final End is a phrase that the Second Doctor triumphantly proclaimed at the conclusion of The Evil of the Daleks when he had absolutely 100% definitely destroyed the Daleks for good.
Yup, no question about it, he got 'em all this time.
Absolutely wiped them out. No Survivors, No back up forces, no chance of any of them escaping. No question about it. Nope, none at all. None. At. All.
The Eleventh Doctor also triumphantly used this phrase once in Victory of the Daleks, before abandoning it when the Daleks foiled him again.