My question is, how does my mother force her to leave and how much time must she give her?
Your mother can't FORCE the deadbeat to leave.
She must do what every other landlord has to do, take the matter to court.
She has to file an eviction action against her "deadbeat" daughter.
A WV landlord who wants to evict a tenant, must have legal cause.
WV defines legal cause as failing to pay rent, violating the lease or rental agreement, or damaging the rental unit.
To evict a "deadbeat" tenant for one of these reasons, the landlord must first terminate the tenancy.
It is recommended that a landlord in West Virginia give an eviction notice.
This site provides an excellent West Virginia Notice to Quit form:
Eviction Notice (Notice to Quit) Form | eForms – Free Fillable Forms
The landlord does not need a reason for the eviction but must provide one rental period of notice. If the lease is month-to-month, 30-days Notice is required. Your mother must give the deadbeat 30 days notice in written form.
An example is linked above.
More information on WV evictions:
How Much Notice is Required in a Month-to-Month Tenancy?
More information and forms from WV Magistrate's Court:
Magistrate Court Public Forms - West Virginia Judiciary