You and your mother should each check with your own insurance providers for a definite answer to your question but normally it would be your mother's insurance that would cover the vehicle. Usually the vehicle's owner's insurance is primary in an accident while a driver's would be secondary.

Your mother would need to place a claim through her collision or uninsured motorist property damage coverages if she has them for the damages the hit and run driver caused. Since state laws and insurance policies and guidelines can vary it is important to each check with your own insurers regarding the situation as suggested above.