'This woman... is she related, maybe this boy's mother?' Theo thought and used his divine eyes. The moment he did this, he was able to see the same blood type running through this woman's veins, it proves that they are related, and as only the boy's mother is said to be a cultivator in the Spiritual Realm, Theo guessed her identity.
'I must kill that boy and also his family... or at least erase the memory of his family and get out of the Naga Empire.' Theo would not leave a possible threat alive. Although they could not do anything with him, the same cannot be said with the people who came along with him.
For Theo, everyone who came with him is more important than the lives of random people he doesn't know.
This woman seems to have noticed that Theo discovered her location and looked through it, and the moment she felt a strong murderous intention, although it was gone quickly, she was able to think it was not a good thing.
