The profile of a BBA graduate from a 3rd tier college that is IMS Dehradun is a below-average profile but when compared to the profile of all MBA aspirants, it’s not that bad as there is every kind of student who wants to pursue an MBA both better and worse than a BBA graduate from a 3rd tier college.
Instead of giving up or dropping a year, you should prepare for the entrance exam, opt for the coaching or online classes, prepare well and give the exam once.
People seem to have this notion that graduation from college somehow affects your chance to get admission at top B-Schools. This is not true at all and B-Schools looks at profile, not college.
So, study hard and secure a good percentile in entrance exams. If you score high enough, you can definitely get admission to these colleges.