Her refusal to make a decision or ask for help sounds like it may be that the kidney problem is causing confusion - that can happen. Or she may have some degree of dementia herself. (The docs never caught my Mom's until an MRA 3 weeks before she passed away).
If either of those is the case, she may not be able to truly express herself in a living will.
Joni Erickson Tada wrote an excellent book (sorry about the blunt title) that really helped me when I had to make these sorts of decisions for my Mom, and help with them for my sister (her kids had JUST reached legal adulthood).
http://www.amazon.com/When-Right-Joni-E ... ie%2C+tadaPerhaps you will find it helpful too.
Be praying for you in this difficult time.