I kinda hope Nezuko is going to get the final hit.

Didn't she lost all her power because she turned back to into a human?

Yeah, but she was also given a lot of blood from Muzan so maybe her turning back into a human is just temporarily. But idk.

or she still has her demon powers even though she turned back human mostly, prolly an effect of refraining from eating humans

I'm not sure if I would like that. It would be too convenient