Security for costs in suits against trustees can be directed to protect public interest and fund the litigation. Courts may, if satisfied after hearing the parties and making such inquiry as it thinks fit that it is necessary in the public interest, direct a trustee-defendant to furnish security for a plaintiff's expenditure or to deposit from trust money a sum sufficient to meet such expenditure; when deposited, the court may make over whole or part of the sum to the plaintiff for the conduct of the suit, after taking security from the plaintiff for refund if required.