It's about weight and volume more than just dimensions, I think. Most 11x30 boards are designed for big or powerful units, so I think that might be overdoing it. In my experience it is easy for guys to underestimate the difficulty that many women have carrying heavy boards. So think weight more than size.

But in general, your wife and daughter will probably have very different priorities than you in SUP choices so frankly the best thing to do, if you can, is to involve them closely in the choice. Pick a few likely candidates, explain how much it means to you that you get something they will be happy with, and then ask their opinions on the options. You may find that the conversation leads to a whole different range of options than you'd considered. In general, this might be a decision better made by them than you. You may have greater knowledge about the equipment than them, but this doesn't necessarily mean that you know better than they do what would suit them. After all, I don't ask my mechanic to choose my car for me. Good luck - it's a tricky one for sure!

JP Widebody. Or any of the other similar shaped wide boards at usually 32" Wide. Very light & easy to carry anywhere. Low rocker profile for better glide. But! The glide & speed gets better as you get stronger in paddling. I noticed this when I first got onto a paddleboard & was concerned that with every paddlestroke the board would swing left then right & not straight as I wanted it to do. But now it just doesn't happen.
So in conclusion I would get the lightest board possible if they have to carry a distance and wide enough for good stability. With low rocker for paddlespeed.
My wife has a 10ft Blackhawk which in my opinion is too heavy to carry. And catches wind too easy & therefore makes it harder for her to paddle against the wind. Or sideways!
Where as I think she would do far better with a shorter board like my 8ft2" Widebody which I found the wind as no problem for me. She hasn't had a go of it yet but I am sure with her balance no problem. But she is a weak paddler. So wind is a major problem but she is getting stronger. She weighs around 60kgs.
Obviously if the balance is good then yeah go less width.
Big boards are for the yoga freaks. Lol!!

I would say go with a board with some length. 10'6" - 11' will be fine.
Allrounders have less rocker and straighter outlines so will naturally track straighter even if they are only a few inches longer than your current board.
I would say avoid anything over 31" wide as it's just more drag for stability they won't need. Also if they are short it forces them to paddle out wide which will turn the board prematurely. Both the Fanatic and the Naish in 10'6" would be good choices.