End of assignment (repatriation) - Madrid-Brussels

Hi,
A friend of mine will return to Brussels after her expatriate assignment and she would like to know which kind of things have to do before departure.
For example: what is the necessary documentation to change the car plate? Where should her go?
Is also necessary to change the drive license, notify to the ayuntamiento (town hall) the residence change, notify to the police station or cancel NIE?
Any useful information or tips for a repatriation will be appreciated
Thanks and regards,