The home is in a Trust. Can the home have a life tenant (life estate) to one of the Trustees?

It's difficult to answer your question conclusively without more information, but there are some general rules that apply. Florida has some special rules concerning homestead property, which is defined as the principal place of residence for husband and wife, in this context.  The parents would not have the legal right to provide anyone but the surviving spouse with the right to reside in the home for so long as either spouse is alive.  I am also assuming for purposes of answering this question that there are no minor children of the parents. If the parents' desire is to maintain the home in trust after both of them die, then the trust can be amended to include a provision that the son who has provided care for the parents would be entitled to live in the home for whatever period of time the parents would like to provide for him. At that point the amendment to the parents' trust could provide for whatever use or disposition of the home they desired. In the situation you have described, the right of the son to live in the home technically would not be a life estate, it would simply be a provision of the trust allow the son to have beneficial use of the home for the designated period of time, including a term that expired upon his death. Your parents may want to consult an estate planning attorney to evaluate their options.