I apologize for the thread necromancy, everyone, but I need to let all of you know how thankful I am for all the advice. It helped me help my dad make the right choices.
On March 31st, Dad and I took Mom to a neurologist and set things in motion to have an MRI that would determine exactly what we were up against. The neurologist said that Mom likely did not have diabetic vascular dementia and nor did she have Alzheimer's. Spasticity that Mom had indicated something else, but the doctor wasn't sure. So we planned for the MRI and kept the plan for amputation on hold.
On April 5th, Mom completely lost the ability to swallow and we took her to the ER on April 6th. The MRI that was on the books was performed, along with CT scans, blood tests and a couple of other things. What we found out was that Mom had white matter disease, hardening of the arteries and microvascular disease. The white matter in her brain was deteriorating, effectively shutting down systems in her body and so we made the decision on Saturday to move her into the hospice center for her final days. She was moved on Sunday, and members of our family came to say their goodbyes. On Monday afternoon, I sat in Mom's room and a wonderful gentleman came and played the harp for us to help Mom relax. Our good friend who's also been doing our hair for years came and told Mom it was okay to let go. A couple of hours later, Mom was dead. Dad was with her when she passed and told me she fell solidly asleep and stopped breathing. I had gone home to check on my dog and relax for the next school day, but raced back to the hospice. Mom had died peacefully which is something I'd prayed that God would allow. He said yes to this one, that Mom would go peacefully when her time came. There was no pain and she was finally free...
Thank you, everyone for your help.