Limited guardians or guardians may be authorized to invest any money in their hands, not needed for the payment of debts, or for the support, or education of their wards, in notes secured by mortgage upon unincumbered, improved real estate situated in this state, or in the bonds or other indebtedness of the United States or of this state, or in the bonds or notes of any city or town in this state, or in the stock of any domestic building and loan association or federal savings and loan association doing business in this state approved by the probate court, or to make deposits of money in any savings bank or trust company in this state approved by the probate court, as he or she shall deem best for the interest of his or her ward. Limited guardians or guardians may also, under the direction of the probate court, invest any money in real estate or bank stocks in this state or in any other safe income producing securities as the probate court may approve; and if a limited guardian or guardian has so deposited any money in any savings bank or trust company or invested money in stock of any association and deposited with the clerk of the probate court the savings bankbook, share certificate or other evidence of deposit or investment, to be held subject to the order of the court, the probate court in its discretion may relieve the limited guardian or guardian of the requirement of surety on his or her bond if the deposit or investment is not in excess of ten thousand dollars ($10,000) and constitutes all of the property of his or her ward, or if there be other property, reduce the amount of his or her bond by the amount of the deposit or investment, but by not in excess of ten thousand dollars ($10,000).