Jim
A bottom quilt is necessary for me but my sleeping bag serves as my top quilt.  My bag does not unzip all the way to the bottom of the bag.  This leaves a foot box so it can’t slip off my feet with it turned upside down over me. 
Magicpaddler
PS
You will want a quilt meant for hanging under a hammock because it will have the shock cords built in to close the gaps between the hammock and the quilt.