Women can also help with the infirmary, there are bound to be some wounded. And gather the families in the keep like cersei did in the battle of the blackwater. 

Tyrion is coming too so they need to set up the feast and make sure everything is presentable like when robert came to the north in the first episode. 

The lady of the house is also running things now so she needs to deal with the daily things the lord is usually responsible for. 

Yoy can also talk to hannibal about being with the forward camp if there isnt much opportunity to help the lady, if the lord would let his daughter so close.