My 74yo widowed mother has lived with us (my DH and older kids) for about 5 years. She has been hoarding and collecting things in her room since she got here. She first wouldn't deal with the downsize in her life. I tried to be gentle in understanding, but the last 2 years have been BAD. She keeps most of her random shopping to her room but it's gone to FOOD now. Canned goods, pantry staples, baking items. Not just a snack, but bags of rice, 6 bags of chocolate chips, gallons of cooking oil. We have plenty of room to store but she shops (with a neighbor friend who takes her while we are at work when we don't need or ask them to). I mention I don't understand why she feels the need to keep FOOD in her bedroom. She snaps at me, "Why do you CARE what I do? It's MY BUSINESS." Which is a stock answer every time I ask a question.
My siblings don't care to hear or support me with any issues that arise.
Cut the food storage off now. It attracts vermin, eventually smells, causes problems with trying to keep everything clean and eventually, when she is gone, the smell will have seeped into the walls and carpet and floor and won't come out.
I know from first hand experience. Not only was I raised by a food+other hoarder (as children we always smelled no matter how clean our clothes were), --it runs in families BTW-- when my hoarder relative lived with us for several years, we believed by keeping it contained to "her" bedroom it wouldn't be a problem outside, but it dropped the house value when we sold the house.
Cut the food storage (and any other smelly stuff) off right now -- even if the ultimatum is to do it or she moves.
FWIW, it is a mental illness. The food is like a safety blanket where the hoarder has control of something when all else is out of control. Check out the site https://childrenofhoarders.com/wordpress/ for more great tips on dealing.
If you cannot move her or she will not move out, a suggestion is to purchase large sealed plastic containers and all food (really, all items) should be stored in the containers with the lids on. This won't stop the hoard but will contain it as it is formed. This process also helps when the hoard needs to be sorted and disposed off.
Good luck.
Number 1 rule should be NO food to be stored in the bedroom.
the last thing you need are mice, and other vermin.
If mom is able to get up, go shopping with neighbors it sounds like she is able to manage. Why is she living with you?
Sounds like you need to have a talk with mom and she needs to begin looking for a Senior Apartment (Long waiting lists so start now) or Assisted Living if she needs some help. Independent Living if she is alright on her own. This could be a Facility with a range of Living options from IL to AL to MC. Or an apartment or condo.
To reply to her "stock answer" it would be I care because it is MY HOUSE and you are to live by MY rules.