Hi Cindy,
Getting C-Diff for an IBDer can be troublesome and possibly moreso than for the person who doesn't have UC or Crohn's. C-Diff is transmitted through stool. So, depending on where your Aunt lives and how clean things are kept and your hygiene habits you could be at greater risk. But, that doesn't mean you shouldn't visit her. My elderly dog had C-Diff for 4 years before she died and with me having UC I was very careful about handling her waste, keeping her clean, and never touching my eyes, nose, or mouth after touching her without meticulously washing my hands.
Go ahead and visit her, but wash your hands with soap and hot water for at least 3 mins. Do this often and NEVER rub your nose or your eye or your mouth without washing your hands - this one way C-Diff can be spread.
Just be wise without being too freaked out.
Cheers,
Elizabeth