$ sudo apt-get update
$ sudo apt-get install grub-mount-udeb 

grub-mount-udeb is installed in your system.

Make ensure the grub-mount-udeb package were installed using the commands given below,

$ sudo dpkg-query -l | grep grub-mount-udeb *

You will get with grub-mount-udeb package name, version, architecture and description in a table

grub-mount-udeb package basic information: