I am very sorry to hear about this. In this situation, a petition for guardianship would have to be filed. A guardian is a surrogate decision-maker appointed by the court to make either personal and/or financial decisions for a minor or for an adult with mental or physical disabilities. After adjudication, the subject of the guardianship is termed a "ward."
Adult guardianship is the process by which the court finds an individual's ability to make decisions so impaired that the court gives the right to make decisions to another person. Guardianship is only warranted when no less restrictive alternative—such as durable power of attorney, trust, health care surrogate or proxy, or other form of pre-need directive—is found by the court to be appropriate and available.
Florida law allows both voluntary and involuntary guardianships. A voluntary guardianship may be established for an adult who, though mentally competent, is incapable of managing his or her own estate and who voluntarily petitions for the appointment.
Florida law provides for limited as well as plenary adult guardianship. A limited guardianship is appropriate if the court finds the ward lacks the capacity to do some, but not all, of the tasks necessary to care for his or her person or property; and if the individual does not have pre-planned, written instructions for all aspects of his or her life. A plenary guardian is a person appointed by the court to exercise all delegable legal rights and powers of the adult ward after the court makes a finding of incapacity. Wards in plenary guardianships are, by definition, unable to care for themselves. It definitely sounds like in this situation that a plenary guardianship would be necessary.
Per Florida law (probate code section 5.030) guardianship requires the involvement of an attorney. The Florida Department of Elder Affairs suggest that people looking to see if themselves or family members are eligible for assistance in programs call the Elder Hotline at 1800-96-ELDER (1***-***-****), so I would suggest you start there to see what can be offered for this young lady and her family. A list of services and agencies can be found here.