Legal Question in Civil Litigation in California

It depends on the nature of the case. A lot more detail would be needed.

A lot depends on what happened during the case. Was the case dismissed? Had the trial actually begun? What did the judge do with the case?

What type of case was it, i.e., what damages were being sought by the now-deceased plaintiff?

Was the plaintiff represented by an attorney in the case? What has that attorney said?

Lots of questions that need to be addressed before anything can be determined.

Some types of claims do not survive the plaintiff's death, but most do. Exactly what must be done next depends upon the posture of the case when he died.

But even if the case can still be pursued, it does not follow that the plaintiff's next of kin are the ones who can pursue it. The plaintiff's claim will probably become part of his estate, so the executor of the estate would be the most likely person to pursue it.