JMHO of course.

c) try to put it off until easter
I wouldn’t do this because I’d be paranoid that Easter wouldn’t be an option. Whenever I’ve “taken an opportunity” I’ve always been immensely thankful that I did.

a) let your dh take your other child for a night or two
Yep I would do this as my first option. But I totally understand (and would expect) you to be fretting about your DD, I would, any mother would. But chances are, everything will be absolutely fine and maybe even quite good (but it does to a large extent depend on the DH in question. Not every DH could do it).

b) go with dh and dd with new bub in tow
I would leave this option open if you can. See how you feel. You might be well up for it, or it could be the last thing in the world you would want to do. You can’t make this decision now, you have to wait till you’re there.

Goodluck.