Help! What’s that series

I read a book series and want to reread them but I can’t remember a lot but I remember there being a house of witches maybe goddesses and one of their names is Nyx, maybe he spelled Nix but she’s the oldest of them and there’s a hunt for objects and one of them is a hair of the oldest witches hair, which would be Nyx’s hair. I can not remember much else. It’s right on the tip of my tongue but I can’t remember the title. It looked through my Amazon kindle, my good reads and even my library account and can’t find it. Anyone know??