For those complaining that Mom shouldn't have attacked the castle in such a way, you need to remember her circumstances: she had justified reasons to believe that her daughter's life was in danger. Since Finne is the daughter of the original heir, she was a potential pretender (or a potential pawn to a pretender). For the nobility, this was a good enough reason to get rid of her. Sumthat with the (false) rumors that Liselotte hated Finne, and she had even more reason to be afraid.
As for why she was not with Finne, I guess we'll find next chapter. But clearly she held an eye on her since she so quickly found out that she was with Liselotte's family.