My Mom will not take advantage of hospice that is available to her free of charge. Any advice?

My dad has alzheimers and my mom is eligible for respite thru hospice. She can get 30 days a year. But will not take advantage. She can take five days or 10 days at a time. When she says things are working good.....they are not. My sister and I are beat from having full time jobs, families of our own and alternating evenings going directly from work and helping to get dad in bed. Sometimes not getting home until 10:00. I don't want her to think we don't want to help. But we need an extended break.