Your parents should read through their the terms of their comprehensive coverage policy to see if it lists changing locks as a part of the coverage. If it does not, than they should speak with their insurance company to find out if other guidelines would allow for the costs of changing locks to be covered by their auto insurance.

This type of claim is not a normal one typically listed as a peril in a policy. So the claims adjuster of your parents insurance company should be able to help them determine what if anything would be covered in their current situation of needing to change locks to protect the garaged car.