N.C. Gen. Stat. § 1-286

Any written undertaking on appeal under G.S. 1-285 must be accompanied by an affidavit of one of the sureties that the surety is worth double the amount specified in the undertaking. The respondent may object to the sufficiency of the sureties within 10 days after the notice of appeal; and unless a surety justifies within 10 days after the objection, the appeal shall be regarded as if no undertaking had been given. The justification must be upon a notice of not less than five days.