Hello, did she lose her hearing in both ears? Or is it just unilateral hearing loss? Is it accompanied by the emergence of ambiguous state of consciousness? Is there an eye movement disorder?
Wernicke encephalopathy can be accompanied by sudden hearing loss. In addition, recurrent vertigo, a single vertigo attack lasted for more than 20 minutes, can cause tinnitus, ear tightness, hearing loss. On recovery the hearing can gradually get restored. After repeated attacks, hearing may not return to the normal level. These are the possible causes to the hearing loss based on your description.
If you can describe her symptoms more specifically, may provide you with more useful information.