The fiduciary commissioners shall have general supervision of all fiduciary matters that are referred to them, and of the fiduciaries in charge thereof, and shall make all ex parte settlements of the accounts of such fiduciaries. Fiduciary commissioners shall have power to summon and compel the attendance of witnesses, to swear and examine witnesses, take their depositions and certify their testimony, and the costs thereof may be charged as expenses of administration of the estate subject to administration.