I have a degenerative eye disease that means the career ladder won't really work out for me down the line. 

When I helped at  our church community food pantry the same sympathy cases would come like clockwork to get the free groceries every time .in fact it got so bad we had to limit a “one chicken per week” policy because they kept coming to get more meat through the week . being financially illiterate is a disease of the mind .

Of course, you can't account for getting a horrible disease in your 40s if you retire in your 30s, but I think the principals behind FIRE is what many people are looking for.Spending within your means, earning supplemental income, maybe not having to work a 9-5 because you earn so much from rentals, etc. 

She wants them topped, which will cost at least $1000, and is claiming her tree guy said they are diseased, so this may not help much anyway. 

Usually, the pre-rental medical screening tests that you put your prospective tenants through would have caught this and any other undesirable diseases they might have. 

Remember the seven D's: death, disability, disinterest, divorce, dishonesty, disease, and dissolution. 

Recently I the doctors discovered that I have an auto Immune disease Ankylosing Spondylitis. 

You knew her illness going in.Also, as the disease progresses, the damage to you house can be bad. 

I think she has a terminal disease but I’m not positive.

Unless they died of some communicable disease, just have it properly cleaned.