rupture in colon and now removed. Has severe infection & much cleaning. Why do ruptures occure?

My mom is back in hospital. She had a hysterectomy, a medium-size cist in the stomach and over 100 gall bladder stones removed 6 weeks ago. She was on her way to recovery, when a week ago she began to complaint of lower abdominal pain and problem eating and having bowel movements. We rushed her to hospital. I were told she had a ruptured colon. She was immediately taken to surgery where colon was completely removed. She was left open so the doctor could clean up feces daily. She had two cleansing sessions. She is heavily sedated and in intensive care.

Questions: Is it possible that her rupture colon was caused during her initial surgery?

What causes these severe ruptures that call for complete removal of colon?

Was it medically necessary to remove the colon? I thought colons could be repaired.

What is the likelihood of a female 77 yr old to come out of this ok? She was in good health for the most part. Only took high blood pressure meds and during her surgery for the hystorectomy, she ended up with fluid and a blood clot in the lungs.