Is my behavior considered correct and normal, or is it impermissible for me religiously to shun my friends who did not visit me to offer condolences after my mother's death? And must I greet them and speak with them despite my unwillingness to do so?

It is not permissible to abandon friends and turn away from them, for Allah and His Messenger have forbidden desertion and abandonment. It is forbidden to abandon someone for more than three nights, even if there is a shortcoming on their part. Pardoning the one who falls short is among the best deeds. Abandonment ceases simply by exchanging greetings, though it is better not to suffice with greetings but to improve companionship, and this is not hypocrisy but rather good character.