I wanna go ahead and say Catelyn Stark.
No, really.
I know she makes a lot of stupid decisions, but all of them are for her kids.
1. When the assassin attacks Bran, she fights him off. She fights him off to the point that Valyrian steel cuts her hands so deeply she can never use the properly again.
2. She travels all over Westeros just to find out who is trying to kill her son.
3. She kidnaps the son of one of her family's greatest enemies just to find out what's going on with the attack on her child. Read: She starts a smurfing war to bring the people who are hurting her children to justice.
4. She lets Jaime Lannister go (weakening her other son's position in the war) in hopes that it will get her daughters back.
5.
Major smurfing spoiler. No, really. Don't read this unless you are completely caught up in the book series. I warned you. Even in death, as Lady Stoneheart, she is STILL doing what she can to get her daughters back.
She's a cool mom.