My mother lives in spring hill and has Alzheimer's her husband has recently showed signs he also may have the beginning stages. Need him evaluated

You can always apply for Guardianship, if your mother does not have capacity, or a conservatorship, if she still does have capacity.  You will be able to get your own information about medical issues, and regulate visitation.  The first step is the evaluation and determination if your mother still has capacity.  If your siblings refuse to allow that evaluation, you can get a Court Order requiring same.