Please do note that there are a few institutes that offer a PGDM course, duly recognized by the Government of India, and the AICTE. Kindly note that only such courses have a huge amount of freedom to select a huge number of electives in every specialization, including marketing.
You should then choose an elective that resembles Event Management. May be, the description of the elective may differ, but you can search for the electives from the prospectus or the website of these kind of institutes. In Mumbai, the number of B schools that offer you such a specialization, is so huge. It is even possible for you to find more than one elective related to event management.
In cities like Chennai, a few private institutes have started courses in Event Management. These are available as part time, or weekend courses. You can get a lot of information through the internet.
Kindly network with other professionals in the field, so that you get the right information. Since I do not know the city you are based in, you will do well to explore the various options available. Regarding the distance education courses, they might give you some ideas, but the distance education courses do not concentrate on case studies, which is a vital input for real world related learning.
You can also meet with reputed people in the field like A R Rahman, or understand how they manage their professional affairs. This will give you some idea about the ecosystem, as it applies to you.