So I need to show Number of registered users / guests / ticketed users for a selected event on a custom event page. So others can know that how many users are going for the selected event.
And when its a event with limited guests, we can show its full house. 
I searched event APIs , unable to find it there.
Thanks for your help on this issue.
Hope to see this in future.
Alternatively, build your own event checkout flow - huge code needed.