$ sudo apt-get update
$ sudo apt-get install apache2-mpm-event 

apache2-mpm-event is installed in your system.

Make ensure the apache2-mpm-event package were installed using the commands given below,

$ sudo dpkg-query -l | grep apache2-mpm-event *

You will get with apache2-mpm-event package name, version, architecture and description in a table

apache2-mpm-event package basic information: