Yes saying Hi and Bye is the polite thing to do. Just treat her like you would a friend.

What did your son tell her? Did he say anything about missing her or that she doesn't answer the phone, etc.?

M-43 W-40
2D - 9 and 5

Emotion, yet peace.
Ignorance, yet knowledge.
Passion, yet serenity.
Chaos, yet harmony.
Death, yet a new life.

RECONCILED AND WISER