$ sudo apt-get update
$ sudo apt-get install libmono-c5-1.1-cil 

libmono-c5-1.1-cil is installed in your system.

Make ensure the libmono-c5-1.1-cil package were installed using the commands given below,

$ sudo dpkg-query -l | grep libmono-c5-1.1-cil *

You will get with libmono-c5-1.1-cil package name, version, architecture and description in a table

libmono-c5-1.1-cil package basic information: