I'm going to make fun of my housemate for saying that homeopathic remedies or 'wellness' could cure cancer
That is silly. How did you find out she had those beliefs?
I found her facebook post to be very ridiculous and irrational.
I am with you in regards to your housemate's silly beliefs, however, they are still your housemate. While they are sharing misinformation, it's important to maintain a home for yourself.
I'm not sure if I should bother. I don't like the idea of homeopathic medications.
Her beliefs should not affect where you live. I would just avoid the conversation with her about it.