They are at your home, but even if they do not, you can still see and tell him, but when he is not, it means that you will never get to know that he is experiencing what.
They are at your house. But even they do not. You can also see and tell him. But if he does, that means you would never know that he had some problems.
They are at your home, but even if they did something bad, you can still see and tell him. But when he's not that mean you will never know that he has something.