Suggestions for a vacant, somewhat historic property

A friend of ours has a beautiful property near SugarLand.

They are away most of the year and do NOT want to rent it out. They do want a company to look after the property and tends to its needs (managing pool, gardening, walk through inside, etc)

Anyone have any ideas the best way to approach this. They do NOT want friends to do it. Paid service & hopefully good service.