Unless the kid raises the bar and takes her actions into the criminal world this is a matter dealt with under landlord tenant law.

If you are where you can keep an eye on things I would suggest being even closer when kid gets served with a notice to terminate the tenancy and the at the end of that time, if she has not left, the notice she is being sued to evict her.

Resesrch the landlord tenant laws so the grandmother does things correctly. Making errors can prolong the action.