Section 9. Sureties on probate bonds shall be inhabitants of the commonwealth, and satisfactory to the judge or register; except that companies permitted by section one hundred and five of chapter one hundred and seventy-five to act as sureties may be accepted in accordance with the provisions thereof and that, if the property of a person under guardianship or conservatorship is composed in whole or in part of any benefit, estate or income paid or payable by or through the United States veterans’ bureau or its successor and exceeds five hundred dollars, the surety on the bond of the guardian or conservator shall be such a company.