Hello, I can't find an answer for the following.

My Nan would like to visit my parents in Australia but she has a number of health conditions. Is there a list anywhere of conditions that would stop her from getting the eVisitor? She would be getting health insurance of course.

Start with your GP.

I've never seen a published list, and it would probably be a case by case basis. Best person to ask would be a registered migration agent - someone like George Lombard who has dealt with a lot of medical cases.
A GP would be very unlikely to have that sort of knowledge about Aussie visas.

I presume you intend to fly to Australia. That’s why I suggested you start with the GP to see if it’s feasible depending on the existing health conditions. It’s a long flight and certain conditions do not behave well on long flights. If that’s all OK then you can investigate further.

How old is she? A medical is required for some visit visas for older people.