Hello, Sanjay!

Yes, you can enroll for M.Sc in Economics after BBA.

For joining a master's degree in economics a candidate must have completed their graduation in any stream.

The candidate applying must have completed a bachelor's degree course under any discipline with minimum 50%.  Along with the above criteria some of the institutes such as IGIDR admit students on the basis of their performance in entrance examinations.

All the best!

Hope this helps!