I'm glad it looks like she's going to be OK. The initial radio call was "unconscious, but breathing".
The incident happened at Eric's Pinnacle, and you would need a steam shovel to get below 60' there.
There are a number of ways a boat can signal divers to ascend without having a siren. Bang on the steel swim step with a hammer, rev the engine VROOM, VROOM, VROOM. But in any event there should be an agreed recall signal. But there's always someone who doesn't come right up or can't come right up (deco, etc.). So there needs to be a plan.
And as Ben said, the Monterey dive boat community is tight-knit.
Chuck