If a town, city, or county acting as agent for a town under N.H. Rev. Stat. § 165:34 spends any sum for the support, return to his home, or burial of an assisted person having a residence in another town or city, or for an assisted person having relations able to support him under N.H. Rev. Stat. § 165:19, such sum may be recovered from the town, city or relation so chargeable or from a county acting as agent for the town under N.H. Rev. Stat. § 165:34. In any civil action brought under this section to recover such sum, the court shall award costs to the prevailing party.