My mom has dementia she is bed ridden stopped talking and eating. She is now eating soft or purée food and saying 3-4 words. Is that normal?

I sure hope you've brought hospice on board by now, as your mom would definitely qualify.
I just wouldn't force her to eat or drink anything as she may at this point be having trouble swallowing. Plus if she's in the dying process eating or drinking can be very painful for her. That's where hospice comes in as they can better walk you through the process.
But to answer your question, yes stopping talking, eating and drinking are all part of the dying process.
Please call hospice today if you already haven't. And yes they are available 7 days a week 24 hours a day.

Yes. Normal. Time to discuss palliative care with MD and Hospice. Let her eat exactly what she wishes any time she wishes to eat it.

It sounds like your mom may be approaching the end of her life now. Do you have hospice on board yet? If not, you may want to call moms doctor for a hospice referral.

Here is a link to a good article with end of life information:

https://www.alzheimers.org.uk/get-support/help-dementia-care/recognising-when-someone-reaching-end-their-life

Wishing you the best of luck with a difficult situation.