re: My Mom has been getting worse with her dementia

Dementia is a hospice diagnosis.....They will not provide sitters, but will send Nurses to suggest meds, pay for meds, send volunteers to read to her or cut grass, etc. Nurse Aides to bath her, and a social worker to help find care needed, and a minister. It costs nothing and provides a lot of help.
Talk to her physician about admitting her and then call a hospice provider you know or trust, and get her signed up...Also Charlies's place is an Alzheimer's respite care facility where you can drop her off a couple of times a week to give your Dad some time away from her care. Good luck..I know it is impossibly hard.