The fact that your mother's insurance paid does not prevent a claim from being filed against the dog owner. The dog owner is liable for the medical bills and pain and suffering, which is an amount in addition to the medical bills based on the medical reports. Dog owner is also liable for any wage loss. The dog owner is liable for negligence. It may not be worth filing a lawsuit. However, if the case is not settled, a lawsuit for negligence against the dog owner must be filed prior to the expiration of the statute of limitations or your mom will lose her rights in the matter forever.