The appointment of a trustee continues until:
Within thirty days after the termination of appointment, the trustee shall file with the court a report of the trustee's activities and all receipts and expenditures, and shall serve a copy on the mortgagor or the vendee by certified or registered mail, an affidavit of service by mail being competent proof thereof. The trustee's account becomes final unless objected to within thirty days from the date of mailing to the mortgagor or contract vendee.
N.D.C.C. § 32-19.2-03