Some hens are more aggressive than others.
Here's what you do:
Never trust her with your children even if she appears to be nice.
EVERY time she comes after you or even thinks about it, grab her! Hold her down with both hands so she has to sit on the ground. Don't say anything. Hold her there for several seconds. Then, let her go.
If she turns around and tries to peck you, take your hand and "peck" her with your hand on the back of the neck or her back.
A chicken never allows another chicken to peck or chase or even glare at her without going after her in return, unless she is lower in the pecking order.
If you show your dominance EVERY time she challenges you (because that is what she is doing), then you are now the top hen.
I am the top hen in my chicken yard. If a hen walks up to me and glares at me when I'm sitting down, she is challenging me and I grab her/hold her down or "peck" her back with my hand to show her that I am the top hen. I have to do this every few days with some of my Buff Orpingtons (I have 26 of them) and some of those hens are just incredibly determined to be above me! Most of the chickens that I have had don't need this treatment.
I have been there, done that with pecking hens. This works for me, but if she is not affected by this treatment then I'd cull her or rehome her. Chickens can peck eyes and with children it's not worth the risk.
(By the way, I never harm/injure my hens. In the next instant they come up to me for cuddles/lap time when I sit in the chair. They just test me, is all.) They are my pets and I never hurt them.