What do the parting words of the poet and her smile signify?

After the airport’s security check, watching her mother standing a few yards away, she spoke, “See you soon “Amma.” These words signify some sort of hope. It shows some promise as well as expectation that she would see her mother again. She might find her alive. So she scatters a smile on her face to pay her mother her lasting tribute. On the other hand she is troubled at heart to leave her mother alone.