High Medicare costs because of sold rental. Should we try an appeal?

See medicare.gov (medicare.gov/your-medicare-costs/part-b-costs/part-b-costs) for premiums this coming year. To have premiums of over $600/month for two, your 2016 annual income would have been in excess of $267,000. (I'm guessing that those here asking medicaid questions would consider that wealthy.)
Having said that, I would review the tax filing for year 2016 --- is that the year you sold the property? Did you count the house sale as income? Perhaps that is the question or perhaps you had another extraordinary income item.

We all try to save money and investments for our old age. When your old age comes, and you have investments to spend on your care, it's all good.