how do i make her flee do i attack her my stupid ai keeps attacking handmaidens i need this and merhant of ehb japanese dude got this achievement dont know if american one is glitched these r last 2 i need to max game out

You make her flee by 'killing' her before the other handmaidens. Unless you have an unbelievably strong companion or you're taking a very long time to fight them, it's more than possible to focus your attacks on her. The colour of the circular targeting marker below her indicates her general HP, as well as the other handmaidens.

Took me a few tries but it is possible. The best way to do it is to focus all your attacks on Jeyne herself. The best way to track her is by her unique spear. She doesn't go into a flame form like her handmaidens do so it is easy to track her. 3 out of 4 times your companion should attack Jeyne as well. Just wail away at Jeyne and try to avoid the handmaidens. It is possible but difficult because Jeyne has a boat load of HP in that fight.