That adult yvonne is the witch itself not the real yvonne, the witch took her body when she disappeared when she was young; it's either the witch killed her for vessel or she died accidentally and the witch took the opportunity to use her body. So yeah she is yvonne but not wholely, her body is but her soul is not. And in the closet? Those are the maids that they assumed that ran away, she killed them all
Yvonne, who got lost when she was a child, sadly died as a child. The Laila bish used her body and made it her vessel. Since then, the bish is living as Yvonne until she got older as she found the perfect vessel to use. The bloody clothing inside her closet are likely to be the maid and the man who disappeared overnight, these witches devour humans like they're food, they suck life forces and kill humans like nothing. One of the main reasons why these Laila witches are banned and sealed.

Okay, just to be sure, so Yvonne is like a witch or something possessing his actual daughter’s body right? He saw she had no reflection in the tea cup? (Which helped him confirm that she is sus af)
And then wtf was that in her closet?? Like bloody clothes? Mens clothes I’m assuming, but just clothes and not a body right?