An elongated colon is a fairly common condition in the elderly. The elongated colon itself does not often cause problems--however it can predispose one for gastrointestinal complications. I encourage you to discuss this situation with your doctor
Firstly, an elongated colon is exactly what it sounds like--a colon which is longer then expected. The colon, or large intestine, is the final portion of your gastrointestinal tract. The main function of the colon is to absorb the final bit of fluid and nutrients (although most is already absorbed in the small intestine) and hold the stool till it can be released. An elongated colon is a condition that can develop overtime or one can have from childhood. Because your mother has it does not necessarily mean you have it (although it is possible).
The elongated colon can cause several problems. Firstly, it can cause problems with movement of the stool out...that is, constipation. Secondly, the redundant tissue can twist over itself and knot itself. This is known as volvulus and causes abdominal pain
and nausea. Thirdly, intussusception can occur, when the colon telescopes into itself--again causing abdominal pain and nausea. These are all fairly rare complications.
You do not necessarily have an elongated colon. Even if you did, there is likely nothing specific to be done if you have no symptoms besides good bowel habits (regular bowel movements, good fiber intake).
I encourage you to talk to your doctor if you have further questions.