@kiero13 The real issue is her desire for revenge. Her and her brother's. That's why Caesar is on her chopping block. Unfortunately, she's too shortsighted. If Noah wants to protect his brother, he'd publically renounce the throne. Doing so would potentially strip his mother of her endgame. However, he seems too weak of a character to do this (which also makes him unfit as a prince—he's kind, but not where it counts—it's blatant how terrible his mother has acted, yet he refuses to cease her games. He must stand up to her.).
I think things might be different if Noah lost his ability to rule. If he renounced the throne publically, stating that he prefers Caesar and will not oppose him, "brothers before mothers", then her drama might not succeed without killing her own son. It would show what is more important to her—her revenge or her child. If she picks revenge over her child, then Noah can act accordingly. Her brother likewise. If they want revenge against the Parlaim family, then why are they trying to hurt Noah?
Noah has to make that clear, but he fails to do so. Likewise, where is Duchess Lancaster in that meeting? Why is she not shown? She's heir, yet is absent from the war council (along with I presume her father, the most powerful family after the Parlaims). How odd.