How did the face of kamala a mother betray her thoughts?

Kamla das while driving to the coching airport saw her mother sitting beside her and dozing whose mouth was opened and face looked ashen like being a corpsed. On looking her face she recalled her childhood fear and the ache of getting seperated by her mother to the cruel hands of death. Even the efforts of her to make her thoughts away were in vain as her mothers face continuously betrayed her thoughts by making her remind about the passing life with time