I am sorry for your loss. Dilaudid (hydromorphone) is an opioid and can cause abdominal symptoms like constipation, distension and others. It is not clear from the history what exact complication she had suffered from. Initially patients respond to lower doses of morphine(opioid) but as days progress, they develop tolerance and require higher doses. That might be the reason your mother might be active earlier on in the therapy. Once larger doses are administered, some undesirable side effects like abdominal symptoms, respiratory depression and others can occur. But cannot say it happens because of the drug or the disease itself. Hope the above information helps you. Thanks.