Which are the Indian Listed Companies who have MONOPOLY in their respected sector?

It is hard to think of monopoly in a sector because that is normally not permitted under CCI regulations. However, there are companies with an edge in specific sub-segments of the industry. That is good enough to give you an advantage.

For example, look at companies like Navin Fluorine, Bajaj Finance, SRF Ltd as all companies which have very unique products or offerings that do not have comparable competition in the market. So more than monopoly you must look at companies that create a special moat in such cases.