(a) Any guardian, in his discretion, may invest any funds of his ward which are in the guardian's hands in bonds or other securities issued by this state. In every such case, the guardian's return shall be filed with the judge of the probate court within 30 days after purchase and shall set forth the time of the purchase, the price paid, and the name of the person from whom purchased.

(b) Guardians are authorized to invest trust funds in the bonds or other obligations issued by the United States government and in the bonds of any corporation created by an act of Congress if the bonds of the corporation are guaranteed by the United States government.

(c) The deposit by a guardian of the funds of his or her ward which are in the guardian's hands, at interest, in any financial institution which is insured by the Federal Deposit Insurance Corporation or National Credit Union Share Insurance Fund shall be deemed an investment and is authorized to the extent that the deposit is insured by the corporation or the fund, as applicable.

(d) No guardian or other person, firm, corporation, or association shall be liable to account for a greater rate of interest than the amount actually received on the investment.