He Wasn't Compatible

Yan Huan's bone marrow was a much better match. It wasn't completely compatible, but still usable. Since Yan Huan was pregnant at that time, the child became Lu Qin and Su Muran's only hope. Lu Qin was willing to kill his own child for his ambitions and future, but karma prevailed in the end.

Su Muran received the life of the children, but that didn't prolong her life by much. 

If that's what Lu Qin was after…

He will investigate the matter and make them give up on the idea. He won't let them lay a single finger on Yan Huan, or her child… though they would never have one in this life. 

As for Su Muran's life, what did that have to do with him?

Sun Yuhan watched him closely after they reached the hospital, as though she was afraid that he would make a bolt for the door. The look in her eyes changed whenever he stopped walking.