I went through that with my parents. Mom being sick and Dad too elderly and frail to do the necessary linen changes, etc. I think he would have wanted either my sister or me to stay there 24/7. As you know, this is hard even with us being retired. There's cleaning up the place, cooking, changing and cleaning her up (shower, etc). Then, there's doctor visits for both him and her. When it came to soiling her bed linen, it became too much. Though I only lived a block away, I still went to bed dreading the ringing on my cell phone. It was exhausting. There was no time for quality time.
Maybe if you approach it to your Mom that the caregiver will do the things she can't do herself. Like cleaning him up if he soils the linens, changes the bed, cleans the house up, cooks. Then, she can just spend quality time with him. She can take a quick break to go to the store. Someone will always be there. You will be able to go there after work and just spend time with your Dad, not run around doing all the other stuff.
Yes, we got someone to come in twice a day. The caregiver was wonderful.
She knew when it was very close to the "time." She came one day, and asked if she could say a prayer for my Mom. The next day, Mom left us.
Yes, get a caregiver.