Because she was jealous of her shakhi and betrayed by her shakhi
she gave sleeping powder to Karu to make AShock asleep. Karu gave him the milk. But AShock still managed to reach karus room before loosing his senses . She misunderstood them and burnt the house. Later she went to save anandi and AShock but Karu was the saviour 
do you think they have a script?