Ask a landlord-tenant lawyer and get answers ASAP
Hello and welcome! My name is ***** ***** I will try my level best to help with your situation or get you to someone who can.
Unfortunately if they are under a written fixed term lease, you can't terminate their tenancy unless they breach the lease in some way. The fact that a family member needs a place to stay wouldn't give you legal grounds to terminate their lease.
So the only way to get them out of the property would be if they voluntarily agreed to move, probably with some payment from you to get them to move out early...
As an aside, in addition to being an attorney, I have also been a landlord for over 26 years...