Why waste an year if want to do MBA post engineering, go for bcom finish your bachelor in 3 years and go for mba!

You would want to do engineering as a backup coz if in 3-4 years you are no longer interested in MBA then engineers get better placed then commerce graduate. If, that is the objective then go for stream which interests you most as you would end up working in that stream. 

Tradionally, engineers did MBA as after working 2-3 years as an engineering, if one wants to be a manager, doing an mba helped in that. This is still valid to some extent. Except for tier 1 engg college (IITs) and MBA from tier 1 college (IIMs)

Conclusion,

• Engg from tier 1 college MBA from tier 1 college - engg stream doesn't matter
• Engg from tier 2 college MBA from tier 1 college - engg stream doesn't matter
• Engg from tier 1 college MBA from tier 2 college - dont do mba
• Engg from tier 2 college and MBA from tier 2 college - engg stream matters

Engineering colleges usually do not matter while getting shortlisted for a company. The Shortlist is generally made on the quality of your CV and it may include a minimum percentage of your academic scores and if you have a prior work experience it also counts. In very few companies it gives you an advantage if you are from a premium institute like an IIT or an NIT.

Also the same goes with your engineering stream which is not an shortlisting criterion in most of the companies. However for example if a production company is coming it will be of an advantage if you are from a mechanical engineering background and it can be used as an shortlisting criterion. But all branches have such advantages in certain companies.