That slap was payback for all the Sheryl lovers/Ranka haters....ain't it a b#tch!
No, I too felt bad for Grace. She was one of the best looking characters in the entire series, and I was hoping that Ranka could snap Grace out of her evil ways before she got whacked, but it was not to be. She, did die with some grace (no pun intended), when looking down the barrel of the rifle there was a look of recognition on her face; it was as if she thought: "I know I've got this coming!" Really sad but we knew it was coming. At least we got to see her birthday suit in cyberspace before she left us!
Yup, payback's a b!tc#, but who says that Grace is really dead? That look she gave could have been of resignation as in "back to the drawing board" rather than "I'm so dead".