B.Com

Hi Shubham,
Weigh your likes and dislikes. Both B.Com and BBA are different in many aspects. If you are interested in finance and accounts related subjects and aspire to be in a related profession choose B.Com. BBA is suitable if you are inclined towards managerial roles.

Getting a regular college would be quite difficult as the cutoff will go really high, you can opt for SOL.

It doesn't matter what you choose. Neither of the courses will help you to be practically a businessman, they teach you theories of different aspects of business. One can be a businessman by working under such industries and knowing how they work in real life scenario. Degrees just polish you in terms of presentation and communication. Also, being an entrepreneur largely depends on your own traits and abilities rather than a degree.

Christ University, Bangalore is an excellent institute for pursuing BBA and B.Com.

You can't get into automobile design after B.Com.
Eligibility
Minimum 50% marks at Higher & Senior Secondary Level (10th & 12th)
B. Tech / BE in any discipline / B. Arch / BFA 4 years / B. Des / Interior Design / Applied Arts with minimum 50% marks.

Yes, you can definitely get admission with such marks in DU and with sc category you'll get good college as well.

You should go for MBA for learning how to do better business.

In case you have failed in 1st year, there is no other option apart from reappearing for the 1st year exams.