You write that "[you]" have the caregiver. Did you hire her? If so, what does your contract provide? Even if you didn't hire her, look to the contract for terms of dismissal.
But as Alva and Real wrote, if abuse is involved, get the police and APS involved.
Call the police. Call Adult Protective Services and report this as an emergency. Be certain to have all evidence to present when they arrive. What abuse are you witnessing? Who hired this person? Does this person work for an agency?
But as Alva and Real wrote, if abuse is involved, get the police and APS involved.