Mu You estimated that this must be the remnant of Lilith's consciousness, possibly sensing the presence of her main body and thus automatically returning to it.
Once Lilith's remnant consciousness returned, the eyes of the girl's head inside the cage opened, and her gaze consistently followed Mu You's location.
Even if Mu You reached out to close her eyes, as soon as he withdrew his hand, she would immediately open them again.
But that was all she did—simply watched him with her eyes open, without any other action.
Mu You guessed that this remnant of Lilith was too weak; even after returning to her main body, she was no longer able to control it to take any further action.
This, however, gave Mu You a new idea: now that Lilith's soul had returned to her body, if he could find all the scattered pieces of her remains and place them into the Resurrection Coffin, perhaps there was a chance to bring her back to life?