Collect all the material to prove that she is being medically treated for her mental condition. This shall include medical prescriptions, record of doctor’s appointments, ashram visits etc. You cannot stop her from lodging the complaint, but you can collect the evidence to ensure that you can prove yourself innocent. You can intimate the Police in writing that you suspect that she will file such a false complaint against you. Lastly, in the event she files a formal complaint to the Police, the only option you have is to apply for Bail and defend the matter in the competent court of law.