so sorry for your family... I hope you can all make this happen!

I'd avoid the YES ticket thing,(too much hassle for a trip this quick)
Just buy from mousesavers site,not hoppers.
I'd take the daughter out of school,and go in May if possible - Check around these boards for notes on crowd levels on different dates-
I'd vote for staying onsite at a smaller place like Port Orleans etc, it's a nice moderate,but wherever you stay,RENT A CAR.

It can be so difficult navigating the buses when you're extra tired and not feeling well.
I've read REALLY good reviews for Wyndham Bonnet Creek, but for the money,I'd check out dvcrequest.com There's a board here for DVC info- you can rent a studio, and have a small kitchen which they may need in their situation-
Also the rooms are nicer than the plain values. I think of it this way,it's the only trip they (may) ever take to DW,so it's worth some money if it can be done.
Plus,the grounds at the mod and nicer hotels are SO relaxing.....
I'm with a pp, I spend carefully,but in a situation like this,I'd spend,and then pay afterward.