Dear Caregiving Adult Children,
Your Mom and Dad both have dementia. Your tasks as caregivers likely has challenging days. Good job on what you do to care for them.
It is hard for me to give you a response without having met your mother. Usually I like to meet the person and thus I can quickly assess more as to what I would/would not recommend to the family as to involvement of your mother with dementia in the dying process and hospice for your Dad.
As a professional care manager, I usually recommend to try to allow the elderly spouse to be involved as much as is appropriate and possible in the life of their spouse and the dying process of that spouse. They live in the same room, so your mother will be seeing her ill spouse, even though she may not process it in the usual way due to her dementia. I find often they have been married for many years and have a history of life together and many shared experiences (both happy and sad ones), and being exposed to what is happening may assist them in the reality of their spouse�s illness and/or death. Although she may not remember the death, with a reminder of some part of the dying process she witnessed she may be aware your Dad is gone, and this may serve to be helpful to her if she asks about him after he is gone.
Actually an assessment is the best way for a care manager to be able to make the best recommendations to you. If you would like me to meet you and your parents to further assess your situation and provide recommendations.