So basicaly, this ending is scrapped, but if he dies before finishing the manga, he consider it the official ending.
but to me Ending C sounds the most interesting
That's when I stopped reading the manga. I consider I have the full story on my shelf, with a perfect ending with father and son at the top of a tree. Great experience but no need for more.
Seems Miura dying before finishing Berserk has spooked a few of the long running manga authors about maybe not getting to finish their masterpieces. Have heard George Morikawa (Hajime no Ippo) also got worried about not finishing Ippo and starting to push the story along a bit quicker.