I had completed my B.Com. What should I do among MBA and CA?

Only 100% commitment towards studies will make you qualified CA. Don't compare it with your UG and other courses percentages to this, it's different. If you want to study without stress, then choose MBA.

You can pursue M.Com or MBA or as per your question, you can also go for CA or CS or CMA, but if you want to do CA then you should be a hard worker. I mean you should give more time to studies, then only you can clear. It depends on you, whether you want to pursue MBA or CA.