Unrealistic scene (spoilers)

The whole death of their mother seems pretty ridiculous.

Not waking up is one thing but to die like that is even worse. First off it would take a lot longer to die from strangulation and her hands were away from her body, not resisting at all. In a situation like that, she would be scratching him violently.

My guess is since I never got strangled, that you would first scratch the hands and if that doesn't work, and I am pretty sure it would for the attacker to take his hands off of you, then you would most likely gauge the attacker's eyes, and scratch the face.

In fact a more effective method would be to rip out the laryngeal prominence. Then when he backs up struggling, swiftly sever the carotid artery at once using his axe or a knife (if you have one). The death should be quick.