I'm sorry for your loss OP.
Both your DD and your DH sound like arseholes.
In terms of the DH laughing... Does DD have form for behaving in thoughtless, non-communicative ways? So he was more laughing ironically at the expectation she might finally be different this time?
Assuming he's a good DH in all other ways, his laughing to deliberately hurt you seems a reach. Especially at a time when he knows you're feeling bad. When people are grieving, their minds can do funny things, and their interpretations of fairly innocent things can be on a knife edge.
Of course, you know your DH best. And if you genuinely think he was laughing to upset you, you've got more problems than an awkward, insensitive DD.
As for your DD... I lost my dad in quite traumatic circumstances. And I was amazed by the people who reached out in support, and those who didn't.
The wife of a cousin (a woman I didn't particularly care for, but whom I only met about once every 5-10 years), reached out repeatedly and often. Checking up with me long after everyone else had stopped. It really surprised me, and she went up massively in my opinion. The next time I saw her, I made a point to tell her how much I'd appreciated it.
But another cousin, the one who I'd always considered a good friend, never reached out once. Didn't hear a single word from her at any point.
I think I just learnt that some people are good at "feelings stuff", and others just aren't. Perhaps there was no maliciousness at all on the part of your DD. She's just someone else who doesn't know what to do, so does nothing.