Hello thanks for asking from Health Care Magic She is talking to someone which is not seen by others. She is also suffering from severe depression. Most likely her symptoms are due to hallucinatory behaviour. Hallucinations particularly auditory and visual are most probably present. This should not be over looked. If the complaints developed suddenly then you should consult a doctor immediately to rule out any organic basis for visual hallucinations. There is possibility of muttering or self talking also. Patients appear to talking to self in muttering. Consult a psychiatrist for treatment and evaluation. Medicines like antipsychotics can prove effective in her situation. Medicines like Olanzapine, Risperidone, Qutiapine etc are commonly used anti-psychotics. Thanks, hope this helps you.