My Mother Has Dementia . She Also Has Osteoporosis And

My mother has dementia . She also has osteoporosis and intermittent recurrent colitis for about 40 years. She had always been a good eater and not an alcoholic. She looks malnourished but she has never skipped a meal. She does not have mood change. She does have some instability at C1/2 with foraminal stenosis and bulging impinging discs etc in the cervical spine. She had a violent husband who often aimed his blows at her head.
She can shower and dress herself but generally reverts to the same clothes for around the house and a different set for going out.
With her recent colitis a relieving GP told me they were concerned about is garnish to the bowel. Her new GP said if she didn't respond to antibiotics and bud open she eioukd need a bowel resection.

What type of dementia does she have and how much can I rely on her instructions to me as her legal Guardian?