Yes, you can buy loss and or repair insurance.
Many hearing aids are insured for the first year or two, so check.
These types of hearing aids rarely need repairs and repair insurance usually costs more than the repairs themselves. Loss is another story. Hearing aids, you and your mother already know, are expensive. If buying loss insurance will give your mother peace of mind, you might want to buy replacement-cost insurance, which covers loss or damage beyond repairs. You usually can buy it through an audiologist.