Intimidation

Of course, it wasn't really about the key. Even if she had it, Mother Lin wouldn't open the door.

Upon hearing this, Old Lady Lin stomped her foot in frustration, her hands on her hips as she scolded Mother Lin. "You're so thoughtless! How could you let an outsider get a hold of the key?"

The 'outsider' Old Lady Lin referred to was, of course, Li Hua. 

In her eyes, any woman who married into the family was an outsider, someone to be wary of. However, Mother Lin had a different view, refusing to fight with her daughter-in-law, Li Hua, over the key.

Mother Lin saw through this, yet she firmly expressed her thoughts. "Li Hua is not an outsider. She is my son's wife, my daughter-in-law."

Mother Lin had been treated as an outsider in the Lin family for decades, and she didn't want her daughter-in-law to go through the same dreadful experience.

Mother Lin was grateful for Gu Zi's return. She was like a lucky star, illuminating their lives.