Both Laila and Mariam find meaning in each other. Mariam lives childless and feels worthless as result. She finds meaning in her friendship with Laila. She becomes a mother figure to Laila and grandmother to Aziza. She sacrifices herself for these two and it demonstrates her deep love for them. It is interesting that she is such a loving mother as Nana, her own mother was constantly hounding her. However, Mariam realizes that Nana was trying in her own way to protect her.
Laila never really feels loved by her own mother who is more concerned with her dead sons. This is why Laila finds meaning in her relationships with Mariam and Tariq. Mariam shows her the meaning of motherly love and becomes an example of how one should treat their children. Laila recognises the strength of Mariam (who never thought of herself as strong) and uses this to stand up to Rasheed.
When Tariq returns, Mariam sees what it means to be treated with respect by a man. Laila had always known this as her own father had loved her and treated her with respect.