MBA in India

Hello Keval,
It's very heartening indeed to know your dreams and that too well in time. Best for MBA is undoubtedly IIM-Ahmedabad. Followed by different IIM' s in India. Of course, you can bid for MBA from abroad too. My advice is IIM.

It's all depends upon your consent.
MBA is reliable at both ends - either in India or abroad and the scope is much better abroad. But if you don't want to go abroad for MBA then you have an option of MBA in international business. This can help you to find more opportunities as per your interest.

There is no specific course for a B.Com or any other graduate. Anyone can appear for CAT exam and prepare for the entrance.

If you are a fresher then you are not eligible to do MBA in Australia. If you want to do MBA, you can do from UK as it is for freshers without experience. It is a one year PG program.
You can not compare MBA in India and abroad as in abroad it is more practical oriented.

IIM is one of the best colleges in India for MBA and it's under 10 lakhs.

Depends on the University and the Currency. It's very expensive to study in abroad. But the certification is valid throughout the world. MBA is a good option but decide how you want to study it and where you want to study? It's actually a great choice.

IIM Ahmedabad has the best placement record in India. You may refer to following link for list of top MBA B-Schools in India: https://www.shiksha.com/mba/ranking/top-mba-colleges-in-india/2-2-0-0-0