Hello Doctor, My Grandmother, 69 Years, Was Feeling Very Dizzy

Hello Doctor,

My grandmother, 69 years, was feeling very dizzy since the past 4 days. On the first day, she told us that her head was spinning too much and she was wobbly and couldn't even stand properly.

After consulting, she took zantac 300 and stemzine, but only one dose.
The next day the dizziness was still there but it was better than before.

4 years ago, she had Bell's palsy (recovered).

Today she went to a doctor and he prescribed : Vestin 8mg
Rantac 150 mg
Stemetil 5mg

I want to know whether this medicine is ok for her and what caused her sudden dizziness.
Is there something we can do to help her?