IF anyone does have a home safe it should be so well hidden that only you could find it and never admit you have it, don't talk about it, it does not exist and never put all or even most of your eggs in one basket. Never go to it inside your home when someone could be watching you. I'm thinking they have been doing surveillance on this home or possibly overheard a family member talking about a safe and followed them home. Kids have big mouths, a home safe or stashed money is not something they need to know about.
Maybe - That assumes the parents are normal law abiding citizens. Not sure that's been established.
It’s a good idea to have a decoy safe as well, with a plausible amount of cash, gold, etc. That is the only one the kids know about. It’s SOP to torture kids in front of parents and vice versa as rapid truth serum...as in this case.