She indeed is holding herself back from transition. From a divine perspective, she is more than ready to go and indeed her life has ended for all practical purposes of growth and learning, having been trapped within the body now by developing dementia. She has experienced and endured the induction of dementia through her own doing in wanting to escape from life and is bearing the karmic consequences that need not persist forever. But in her state of inner torment and confusion, she is looking in the wrong direction. She is not looking for a solution bringing her to a place of wonderment and love. She is trying to reconnect desperately to what she has known before, so her free will is strongly choosing to stay earthbound, and as long as that is so, the higher self will likely accede to the requests and that natural perspective.
This is why many, many people linger so long in a debilitated state serving no seeming purpose, it is because they are trying to cling to the memory of what they had before and cannot envision something different, especially not something much, much better through moving in a new direction that seems to entail the risk of losing everything. You can do a consultation with higher self and explore the issue with respect to transition decision-making and its ins and outs with respect to her as an individual. This could be quite enlightening for you and will help especially, in coming from that source.
We understand that it would be a blessing for many to have a way to hasten the transition when life has seemed to lead to nothing but further decline and a level of suffering with loss of function that is irreversible and progressive. We agree, in general, that this is a most unfortunate stage that all too many go through, but in each case, there are reasons, there is a predicate and a destiny being served that satisfies the karma involved in creating the dilemma in the first place. This will not be apparent on the surface but is always the driving force, so there is a method to the seeming madness that will not be apparent except with a deep understanding of the karmic history of the individual.
There are situations when transition is allowable and may even be recommended by higher self, but still resisted by a level of the mind within the person and that will rule. So the use of subconscious channeling is the key in helping such individuals redirect their thinking and have sufficient healing to make a better choice about their future knowing they can return to the light and this will be an answer for their suffering.