Can anyone please find this old movie from the 60's or 70's?

I have been trying to find this movie for about five years now. It is about a group of college fraternity hopefuls that are challenged to stay in what is supposedly a haunted mansion in order to fulfill an initiation. They get locked in and soon are being killed of one by one by two brothers that have been in hiding in the mansion. I remember a sceen where they had fallen into some ditch and found themselves in the basement where there was a dining room where other family members were placed seated after being murdered. You could see all of the bodies seated around the table with cobwebs hanging from them. This movie could also be from the very early 80's