Supratim, Aman is totally right. And there is one more thing you can do if you are so sure about doing an MBA. 

You can go for IPM courses which IIM has started for 12th pass students. 

There are currently 2 institutes providing this course. IIM Rohtak which has started this year and IIM Indore.

IPM is a 5 year course, 3 years (BBA in Indore and BMS in Rohtak) and 2 years MBA. You have a plus point here that after the bachelor course completes you can switch the college. You can give CAT and get into another IIM like Ahmedabad or Bangalore or any other private college. And you will get the bachelor degree from IIM.

IPMAT is the entrance exam for this course. Feel free to enquire.

Hello Supratim

There is no such ideal UG course for MBA. If you go to a good college for UG, that adds a brand value for you in the PI rounds -that too just a little bit. If you have 90% types marks in UG - brilliant - that adds value in the PI room.

Go to a very good reputed college or go to a college which gives lots of marks - the stream does not matter in selection. Though, these three streams are most popular in MBA colleges:

Engineering

B-Com

BBA

Other common streams are:

Economics honours

Maths honours

BCA

BSC IT

MBBS

But, anyone can do an MBA! Stream doesn’t matter much!