Evil is human concept - it is an idea - it does not exist in reality. Evil is subjective to each of us like if something is good, tasty, just, or vile.Well can she prove it?
Where is her evidence? Where is her objective standard of evil?
If someone said disease is evil then that means they find disease to be evil subjectively. There is nothing to prove since it is a human opinion, not an objective fact. You can believe that disease is awesome and you would not need to prove that - its your subjective opinion.
If you claim evil is objective then you are going to need to prove that.
You are confusing objective and subjective again.