The executor or administrator shall file with his final account a written statement, under oath, of the names of the heirs or devisees and legatees of the estate, so far as known, specifying particularly which, if any, are under the age of twenty-one years, of unsound mind, or convict of felony; the places of residence of each and their post-office address if they be nonresidents or, if the post-office address be unknown, the statement must aver that diligent inquiry has been made to learn the same without avail and giving the names and places of residence of the guardians of all who have guardians, so far as known.