Having metastatic breast cancer spread to bones. Pain in the hip area. Not on treatment. What care can I give?

My Mother inlaw is coming to our home for her last days. Metastic breast cancer now in her bones. Very painful in her hip/ groin area. She does not want to treat, she is ready to say good bye. We have hospice coming. We are hoping to get her pain managed and give her comfort care. She is 81 years Any information about how this may progress and length of time will help us provide the best quality care we can. We are not with out experience, my father lived with us for the last 2.5 yrs and died a few months ago at 96 years My husband cared for his father with ALS. I cared for my mother post a stroke and for my late husband who died of cancer age 58 Any information of what we may expect/encounter will help us. Thank you in advance YYYY@YYYY