I'm very sorry to hear about your mother. She has certainly lived with MS for a very long time. Similar questions get posted here occasionally, but there is one which has received a great many responses. You may find information and comfort in the responses to this question.
One of the persons who offered information in the previously linked question, gave these resources for further information regarding what to expect at the end-of-life and hospice care for MS patients:
On this page, please find the document listed below the main article and video, called "Advanced MS: a guide for families" .
Print it off and refer to it often as things change.
for those in the UK, there is a similar link:
Read both, as each one has important info.
to read more about Palliative care (things to make the person feel better, but do not count as a treatment or cure) :
I hope that your family is doing well and that your mother is comfortable. It makes me sad to hear of patients who do ultimately die because of what MS has done to their body. My thoughts go out to you, your mother, and your family.