After learning from Victoria Dodd that Van Ness was responsible for the goings-on in the Van Ness House, the Winchesters set out to locate and destroy Van Ness' bones, not knowing that Van Ness was following them by attaching himself to a key that he slipped into Sam's pocket. Looking on the Internet, Sam was able to discover the location of Van Ness' bones, but Van Ness chose that moment to attack. After Dean destroyed the key, Van Ness was bounced back to his house and the Winchesters went after his bones with greater urgency since they knew Van Ness would go after Bobby Singer and Annie Hawkins.
Reaching the mausoleum, the Winchesters quickly broke into his grave and began a salt and burn upon the bones. Dean ignited the bones, destroying Van Ness' ghost just as he was in the middle of destroying and absorbing Bobby's ghost, saving Bobby.