Is it againsy Ca law to take your kids on a trip out of the state without telling husband? My daughter is thinking about divorice but hasn't started the proceedings yet?

If the couple in question is still together and raising the kids then probably not as the legal presumption would be that both parents knowingly consented for their children to travel out-of-state. However, if your daughter is planning on taking her kids out of the state and not bringing them back, then filing for divorce from their father he could possibly charge her with kidnapping and make things very difficult for her legally. This could subsequently be used against your daughter to deny custody or visitation. If she does decide to file for divorce advise her to do everything "by the book", 100% legal. That way her husband won't have a leg to stand on if he tries to deny her custody or visitation.