I'm very sorry for your loss.
Around here, the funeral home will give you the cards from the flowers, a list of those who made donations, and the guest book along with the acknowledgement cards to send out.
We normally have a guest book at home too for people who bring food. We ask them to sign and list the food they brought. It makes it easier to keep track of who the pots and pans need to be returned to. We usually send out cards to these people as well.
We have also sent cards to hospice workers, nurses, doctors, and friends who made many visits and helped out.
It really just depends on what you are comfortable with. I would say the flowers and donations should be acknowledged and everything else is up to you.
Once again, I am very sorry to hear of your loss.