I went to a nursing home to donate it and they didn't even let me finish taking, and didn't want it..This mattress saved me after getting up every night for 2 years, allowed me to go to bed at night , I just thought it may help someone else..ive listed it on craigs list, and no one wanted it as well. SOOOO I wondered what to do? throw it out and forget it?
If it is an air-pulsing type maybe contact the VA, church, synagogue or elder-assistance or hospice/homeless center?
They may not be able to handle the bed directly, but might be able to refer people to you.
If it is a "regular" mattress or foam you may just have to take it to the dump (also, if your Dad died in bed some people have the heebie-jeebies about that).
Objects in this world are created, objects are discarded. Just the way of things.