The following is an attempt to explain a difficult subject:
The gall bladder contains bile, which helps to digest food. Therefore the gallbladder throws the bile into the intestine via a duct called the bile duct. The pancreas produces pancreatic juice, which also helps digest food. Therefore the pancreas throws the pancreatic juice into the intestines via a duct called the pancreatic duct.
Unfortunately, the bile duct and the pancreatic duct join before they empty their contents into the intestine. Therefore diseases of the gall bladder can affect the pancreas.
Your mother has developed pancreatitis from gall bladder disease. Pancreatitis is a serious disease. The treatment depends on the patients condition. Sometimes surgeons operate only on the gall bladder, allowing the pancreas to heal on its own. Sometimes the diseased pancreas may not heal on its own, and may cause danger to the body. In this situation the surgeon will remove the diseased portions of the pancreas, as well as any surrounding pus. The surgeon will also usually remove the diseased gall bladder.
After operation the patient is often not permitted to eat. Therefore the surgeon usually inserts a tube from the abdominal wall into the intestine for feeding. Pancreatic surgery can be dangerous, and the recovery can be prolonged.