What is the best type of mattress for a hospital bed for assisted living?

It can't be coil because it won't bend to the various positions of the hospital bed. so the answer is foam and waterproof.

You might want to get an alternating pressure mattress pad for on top. It helps prevent bed sores.

Hospital beds usually have plastic covering and as said is foam. Make sure it's a firm foam.

Actuallly, I found a place in my city that makes custom mattresses, so I bought Dad a 'soft' coil mattress for his adjustable (head and foot) bed. It's firmer than foam, so he can get in and out with less assistance, but it still allows the bed adjustments, which are done with a hand-held remote.

Thank you all. I found both types online so I was wondering. I thought the coil, or innerspring, would hold up better.

If your budget will stand for it, alternating air plus Tempurpedic type foam. The down side of this combo is that it makes a fall off the bed relatively easy. Especially if the patient has REM Sleep Behavior Disorder (RBD.) But it is extremely comfortable.

I should look at the bed manufacturer's website and see if they recommend any mattress models. That way you can be confident it'll fit tidily, too.