The county legislative body has the power to appoint or elect a public administrator, a public guardian and a public trustee, who shall hold office for four (4) years, and who, before entering upon their duties of the office, shall take the oath by law prescribed for administrators, guardians and trustees, and shall give bond, with good and approved sureties, in such amount as may be necessary and amply sufficient, in the discretion of the county legislative body, to protect the estates, funds, and property that may come into their hands, which bond as to amount may be increased, from time to time, by the county legislative body.