Hi Amy,
I would question the Hospice people as to whether hospitalization for this problem might actually be considered palliative (comfort) care rather than an attempt to save her life. It really does sound like she has a blockage, and from what you say, that is to be expected, but to make no attempt to keep her from suffering because of the blockage is inhumane on the part of medical personnel. Surely in the hospital they could relieve her symptoms without doing further surgery - decompression of the bowel with a Miller-Abbott tube would clear stool that isn't being passed and stop the vomiting. Administration of parenteral nutrition and lipids would result in very little if any production of stool, while at the same time keeping her hydrated and supplied with vital nutrients. I see no reason why the Hospice staff shouldn't be able to help you manage this kind of therapy once she comes back home - if they can't, find out if you can get visits from a home health nurse in addition to the Hospice staff.
I am a firm believer in the principles of Hospice, but they are like any other health care organization - their policies aren't infallible. If you don't get any where with the Hospice people, I definitely would go around them and contact your mom's doctor yourself. A patient or the primary caregiver has the right to do that, regardless of whom is in the home helping with care. If the doctor agrees to look at providing more aggressive palliation and Hospice puts up a fuss, you're gonna have to go with what you think is best for your mom. She probably is eligible for home health care, or in light of the situation, if she has insurance, the insurance company may be willing to work with you to find alternatives other than Hospice.
I don't know what kind of answers you're going to get, but if you want to see your mom spend her days with more dignity and less suffering, checking it out certainly is worth the risk of being told no.
I wish your mom the best that her health can be, and I hope that you and your family will remember to take good care of yourselves as well as her.
Sincerely, Tre