My grandma is not suffering from dementia or Alzheimer’s and is pretty clear in mind. When any of us (grand children) or my dad are around she is very sweet, but also has outbursts of needing our help with very small tasks that she can do on her own. My mom has shared with me that my grandma is verbally abusive to my mom when no one is around and accuses her of abusing her and not caring about her. She also takes any chance she can to bad mouth my mom to other people. How do I help support my mom and care for her so that she is not running herself mentally and physically into the ground caring for my grandma?
If by chance Grandmother has a UTI, it can be corrected with antibiotics.
If Grandmother is still acting out, it is time for a village to help your Mom with Grandmother's care. Otherwise your Mom will crash and burn, and that is a difficult place to crawl out from under. Believe me, I know.
Also, whenever a grown child lives with a parent, or vise versa, the parent/child dynamic start in.... thus Grandmother becomes the parent once again, and your Mom is viewed as the child. Lot of clashing happens.
Have you offered to stay with your grandma so your mom can get away by herself for an afternoon? Or offered to take your grandma overnight so your mom can have some peace and quiet?
If you throw your hat in the ring that's 2 family members who are caring for your grandma. When it takes 2 family members to care for one person it might be time to consider alternative living arrangements such as an assisted living facility.