Fight her

The best way is the straightforward way. You will go and fight her yourself and bring her to custody. You will take your dagger, but you do not intend to kill her with it... Let's hope the intimidation will be enough to make her submit!

You appear at her house with some ropes in one hand and a dagger in the other.

Sofia: Lady Lily, what an unexpected surprise, I have been looking for you! What do you intend to do with those things in your hands...?

Lily: I am here to take you into captivity. Do not resist and it will be over quickly! I do not want to hurt or kill you, but if you force my hand both outcomes are possible... Come what may, your reign here will end, once and for all!

Sofia: Are you threatening me Lady Lily?

Lily: The Church will decide your fate.

Sofia: I AM the Church!

Lily: Not yet!

Sofia: It is treason than...

She takes a knife out of her pocket and charges at you.