He loves her daughter so much

It’s one thing to seek permission and it’s another thing to tell the others where you are going or where you will be just in case of an emergency that’s okay. But when you say that your sister has to seek for permission to go out with her friends at the age of 55 I find that quite absurd. I mean the only person she should seek permission from us get husband because it’s prudent that she does that. But for your dad I think it makes perfect sense for her to repaort to him that she would be going out, because that is a sense of respect which is expected from children to their parents. And again you are under his roof so rules should be adhered to while you are there. I remember when I was in college my dad always used to make fun and say that anyone who is over 18 is his neighbour so we should be responsible enough to do things right, though he still provided for our needs until we could stand on our own. I guess when someone turns 20, they should be left to do certain things in their own, to learn responsibility.