Whoa I think you're getting confused. Her dad has stated he last heard from her via text at 10:43 the Monday before, not the night of. He said that was when he last heard from her but that she stopped to get her mail Tuesday, but he wasn't there to see her.
Now, as I re-read the article I see:
"Her mother said her date dropped her off at her house. Heather called her roommate to tell her how she had a great time. That is the last time anyone will admit to talking to her."
The wording here confuses me. Twice actually. 1) "dropped her off at her house." Is the second her meant to be Heather or meant to be her Mother? I just jumped to Heather's house because it made sense after a date to go home and change. But if she was dropped off at her parents house and they drove her home.... why didn't she want her date to know where she lives? Also that would explain how her last known location address would come to be, if her parents dropped her off. Unless they didn't and she had called her mom and then her roommate and the police confirmed with the date her last known location. (dang my head hurts now.)
Someone must have told them about the roommate call. I would guess the roommate herself, or the cops released it with the other info. Which would maybe account for the second confusing wording "admit to talking to her."
Sounds like they know something we don't know...
http://www.wmbfnews.com/story/24273295/horry-county-police-investigating-missing-woman