My take is a little different. You and DH should take her out for a nice dinner, and then that is the end of it.
I say this because there's risk involved when you start asking others what they're doing. I know because I've seen it at least twice. OP, you and your DH may have common sense and respect for her wishes. Others may not. They're well intended, but they just can't let her go quietly.
I would write or talk to her and just acknowledge that you know she doesn't want a party, but the 2 of you would love it if she'd let you take her out to dinner. And then, obviously, if you get invited to an offsite event she has sanctioned, you could attend that, as well.