MBA/PGDM

You must appear in MBA entrance exams like CAT, CMAT, MAT, etc. to get admission in a good MBA college.

Check out this link:
https://www.shiksha.com/mba/course/post-graduate-diploma-in-management-shri-ram-murti-smarak-international-business-school-srms-ibs-lucknow-127995

Check out this link for top distance colleges:
https://www.shiksha.com/mba/articles/top-10-institutes-for-distance-correspondence-mba-blogId-6301

To get admission for MBA you must appear for the entrance exams like CAT, CMAT, MAT, etc. and get a good score.

There is no age bar for doing MBA. You are eligible to do MBA even if you have 3-years or more years of gap in your education. You may have to provide justification for gap years during HR round of interview. If your MBA academic performance and job selection process performance is good, any HR recruiter will condone your gap years.

I would suggest you to go for most promising specialisation i.e CSE from UEM, Kolkata to get good placement assistance. https://www.shiksha.com/university/university-of-engineering-and-management-kolkata-47398

For better placement, very good job and career growth MBA is useful after BMS.
I advise you to gain 1or 2 year work experience and then go for MBA.