Top-ranked North Dakota State, the two-time defending NCAA Division II champion, completes its pre-holiday schedule with a pair of dual meets this week.    The Bison, who won the St. Cloud Invitational on Saturday, wrestle at Southwest State (Minn.) on Friday before returning home Saturday to battle Northern State.    Second-ranked South Dakota State plays host to Minnesota State-Moorhead on Thursday in its last competition before Christmas.    Third-ranked Central Oklahoma and fourth-ranked Nebraska-Omaha are both off until next month.    No. 5 Ashland (Ohio) is scheduled to play host to Baldwin-Wallace on Saturday.    Ashland also has two meets next week, traveling to Muskingum on Monday before wrestling at Mercyhurst on Wednesday.    Sixth-ranked Pitt-Johnstown wrestles in the Clarion University Duals on Sunday, meeting Lock Haven, Ohio and Kent State.