Cal. Civ. Proc. Code § 416.70

A summons may be served on a person (other than a minor) for whom a guardian, conservator, or similar fiduciary has been appointed by delivering a copy of the summons and of the complaint to his guardian, conservator, or similar fiduciary and to such person, but, for good cause shown, the court in which the action is pending may dispense with delivery to such person.