IIM Ahmedabad - Indian Institute of Management Vastrapur Answered Questions

IIM-Bangalore has some strict percentage criteria for boards (80% above in 10th and 12th, if I am not wrong). So, B might be off the books, but you still seem to have a decent chance at C with a high percentile. I don't want to be blunt, but you will really need to nail CAT hard. Otherwise, try looking at ISB, etc. wherein the admission isn't so marks based.
Good luck.

I would recommend you to consider Executive MBA as it supplements your rich experience and helps you place yourself in relevant management position post your 20 years of experience. You can look at EPGP (IIM B) or PGPX (IIM A) in case you are planning to do MBA in India. Moreover, you can also look at 6-month long courses offered by IIM A/B/C for retired army executives to introduce them to the business world.

You can pursue your executive MBA in any of the top B-schools in India, may it be IIM A or ISB, all are at par with each other. You will get the required push forward for your career and the right people to mingle with to get your grey cells working. Personally, I would recommend PGPX offered by IIM A.

IIM's I would say aren't the end of the world and you can very well reach similar or greater heights in your career despite the IIM tag. You can look at other Indian MBA B - Schools or Foreign B-Schools, that don't give as much weightage to 10th and 12th percentage like ISB.
Also, I would say it is important that you introspect a bit about your career and look for ways to progress where your past profile would not be a hurdle.