Yes, I had the same feeling about "Happy New Year". I thought, "Yeh, maybe for you, but for me, I'm not so sure". I just HNY'd them back and went on.
Your mom needs to eat. Try small snacks two or three hours at a time. It may seem more doable for her, you'll get the calories down, and she will be less nauseated. Patients are notorious for not being hungry and nothing tasting right. You can't accept those excuses, and just keep encouraging her. Don