Azrail knew the feelings that his mother was hiding behind her calm smile, even with the issue of Yurou, she was deeply afraid for him. Listening to his journey, she was filled with dread for him. It was just that he was blind not to notice or see any of it.
She was his mother, and he was her son. How could he not tell what his mother was feeling? She was afraid for him, she herself has gone through the difficulties of life, and she knew the dread of weakness. Hence she dreads what he would go through.
Her mixture of emotions was completely complex. On one hand, she loved his desire to climb above all and never give up, but on the other hand, she wished for him to just reign over this realm such that he won't face any problems above. She didn't want him to go through pain, yet once again she knew that pain and suffering are one of the greatest ways for growth.