hi,
For Geodude, I would go for B. Golem's best stat lies in his defense. I therefore would bump up his other two stats as much as possible. Option B having higher overall iv, cp, and atk iv, definitely will be your best choice.
Same with Onix. Steelix's greatest stat lies in defense (ridiculously high). Option C has the best overall iv, cp and atk iv (better all around stats). Best choice.