My vote is for C, though I'd change a few things.
I'd put a butt end similar to the one on the tanto to aid in retention. I'd also slim out the handle slabs for both comfort and concealability, more a then b.
I have never, ever been in a knife fight, and save for olympic and historical fencing, don't ever plan on it. Still, from my unility type tasks, I think a mild sweep with a decen t point are good things. Allows for some slaching/belly of blade cuts, gives the front a larger sweet spot for chop motions, and puts the point in line with yopur arm for accurate thrusting.
Tanto's alsways seemed like think front ends that felt like thick front ends to me, and no belly is no good. While I like straight line knives like a, I don't think they lend them selves to ergonomic movement like swept blades.
I'm not sure whya the furrel is for, maybe weight savings? If you loose a little girth in the handle and cover the rib hurting if you fall on it tang section of the handle with a hooked, hand retaining end, I'd say you would have a winner
