Hello and hope you are doing well.
It's likely that she is suffering from facial nerve palsy. It is the nerve which supplies the muscles of the face. The nerve can get swollen, inflamed, or compressed, resulting in facial weakness or paralysis. The can cause inadequate closure of the eye, drooping of the mouth and dribbling of saliva.
Treatment depends on the severity. Some cases are mild and do not require treatment as the symptoms usually subside on their own within 2 weeks. For others, treatment may include medications and other therapeutic options. To find a cure she will need to consult her primary care physician for proper assessment.
Hope this helped and do keep us posted.