Visitor insurance covers for any new, unexpected sicknesses and injuries.
However, it does not provide coverage for preventative care such as flu shots and vaccinations. It is recommened that your mother obtains a flu shot from her health provider at home if she would like to get one.
A refund applies only if you buy for a certain amount of time, and for some reason the policy is cancelled prior to the end date. For this, you would receive a refund for the remaining days that were unused.
Unfortunately, you will not receive any type of refund if you do not file a claim during your mother's stay in the US. The reason for this is because even if you don't file a claim, the insurance company still carried the entire risk throughout her stay.
Try to think if it this way: when you have auto insurance and you don't get into an accident, you would never expect to receive a refund because the insurance company covered you for the duration of time that you paid for.
Hope this information helps.
Insurance rates are regulated by law. You can't find the same insurance plan for a lower price anywhere else