Her DIL lives in the house now.
What can I do so I can care for her, work, take care of her, and my house without losing my mind?
She is on Medicare so that's good and as. She doesn't receive any government subsidies.
I Have a big issue having someone come in to care for her. She's paranoid. And as you all know who do you trust?
Is Mom able to understand that even though she is living with you, she still needs to pay the mortgage [if there is one], the real estate property tax, household insurance, umbrella policy [extra coverage, well worth the cost], all the repairs that are needed such as replacing appliances when they stop working? Fixing a leaking pipe? Fixing a leaking roof?
Is there a rental agreement between Mom and her daughter-in-law? I wouldn't be surprised if there isn't. Hope the DIL in paying fair market rent for the house, if not, that could cause a red flag if later down the road Mom needs to use Medicaid [different from Medicare] for nursing home care.
Whatever you do, keep on working, otherwise you will lose more than just your salary. Can Mom afford to budget for agency caregivers to come to help her while you are at work? Caregiving agencies are licensed, bonded, insured, and have workman's comp for their employees.
It may take time to find the right match for your Mom, so ask the agency to send numerous caregivers to try out. My Dad had such caregivers, and they were with him for over a year. They were a Godsend for him, and for me.