Would it be beneficial for me to pursue graduation/post-graduation or MBA in event management?

Doing post-graduation would be a better option. The questions which are asked in the entrance are based on general awareness as events are all about how well you know your surroundings. And when you are in an interview the first question which interviewer asks is why do you want to opt for events?

If you are looking from time perspective, then MBA is better, because you just need to focus towards the preparation to crack the entrance, and then you will easily get any well reputed MBA institute. After completing two years, you will be placed according to your talent.