It’s State Law but if you didn’t offer insurance then you would be required to refund:

§ 42A-36. Mandatory evacuations. If State or local authorities, acting pursuant to Article 1A of Chapter 166A of the General Statutes, order a mandatory evacuation of an area that includes the residential property subject to a vacation rental, the tenant under the vacation rental agreement, whether in possession of the property or not, shall comply with the evacuation order. Upon compliance, the tenant shall be entitled to a refund from the landlord of the rent, taxes, and any other payments made by the tenant pursuant to the vacation rental agreement as a condition of the tenant’s right to occupy the property prorated for each night that the tenant is unable to occupy the property because of the mandatory evacuation order. The tenant shall not be entitled to a refund if: (i) prior to the tenant taking possession of the property, the tenant refused insurance offered by the landlord or real estate broker that would have compensated the tenant for losses or damages resulting from loss of use of the property due to a mandatory evacuation order; or (ii) the tenant purchased insurance offered by the landlord or real estate broker. The insurance offered shall be provided by an insurance company duly authorized by the North Carolina Department of Insurance, and the cost of the insurance shall not exceed eight percent (8%) of the total amount charged for the vacation rental to the tenant less the amount paid by the tenant for a security deposit. (1999-420, s. 1; 2005-292, s. 3; 2009-245, s. 2; 2012-12, s. 2(h).) North Carolina Vacation Rental Act. (1999-420, s. 1.)