She was vulnerable because she loved her son.
I was distracted during the set up, but half way through the ma'am of the house was saying that the son had problems, that they had over come together with he help of the rich white family.
I remember Phillip said that anyone who believes in god can't be trusted because they are unpredictable, ie can't be trusted to look after their best interests, he also was sure that he needed six months to turn her to his way of thinking gently.
Oh... Was this comparable to Abraham sacrificing his son when god told him to?
In her heart she decided that God needed her son to die, and then changed her mind when a pillow when over his face.