My mom is 87. She is bedridden with a slight case of dementia. She knows me. I have to purée her food because her bottom teeth are bad.

Pureed food is very unappealing and I'd turn it away myself. Offer your mother a homemade milkshake and see if she takes 1 sip of that or drinks the entire glass. Then offer her soft foods, yoghurt, ice cream, smoothies, applesauce, watermelon, etc. Then call her doctor to see if a hospice evaluation is in order.

Good luck to you.

Do you have Hospice helping you?
As a person reaches End Of Life they do not need the calories that food provides like you and I do.
And she does not experience hunger like you and I do.
The growling that you hear may be normal bowel sounds (that is a good thing)
The growling that you hear may be gasses that are in the stomach and bowels.
If mom is hungry she will eat.
Offer food and liquids. (It may be that you have to thicken liquids so that she does not aspirate.) Hospice usually provides the product to use. But you can purchase it it in the pharmacy section of grocery stores or the pharmacy. the product that I used was Thick It. There are others on the market.
Try foods she really likes.
Typically sweet foods will be consumed.
Ice cream, (be careful if she does need food thickened ice cream is considered a liquid as is any gelatin). Pudding, applesauce,

Do not force her to eat or drink. if she eats only a little bit wait a while and offer again.

There is no such thing as a "slight case of dementia." When it's there, it's there, and it's never going to get better, only worse.

Your mom needs to see a doctor. In the meantime, try Ensure. It comes in a can, tastes good, and your mom might like it a lot.