I know a married couple in their 80s, she's been mentally abused and controlled by her narcissistic husband for decades. He controls everything, money (he gives her a housekeeping allowance), where she goes, what she's "allowed" to do, who she's "allowed" to see. Every single thing she does is monitored by him. She is gonna need some serious help when he dies, the whole family will. Too late for that family.

I you have someone in your family like that, the only way to deal with that person is if the whole family pull together and force the narc to change, they are weak, they will have to accept they cannot keep behaving so badly and not suffer the consequences of their behaviour.