Where to get help for my brother whose property tax increased and the reason given was because he is not living at home?

My brother is currently in an assisted living facility , but still has a home near by. His property tax increased from $800. last year to 3,000. this year. He is a 91 year old WWII Vet . and the reason given was he is not living at home. If he was living in a nursing home instead of an Assisted living home it would be different. This is in Hancock county, IL. They said it is the law. Is there anyplace to get help. I am his sister and have Durable Power over him. I have been taking care of his bills ect. for the past 3 years. His property tax actually gone from $400 to $800 and this year $3,000.