I like B the best as the plain band combined with the bezel ring look great with the roundness of your solitaire. It would probably look best in the same metal rather than yellow gold though.
To my taste, C is the best look. I do like A, but I think it's not got enough finger coverage for that giant soitaire. The proportions of it is just a bit off when paired with the e-ring. I do think it is a beautiful ring, though.