Statement I alone:

Information about only 4 persons A, B, E, and F is given. No information is given about the position and direction of D.
Statement I alone is not sufficient.
Statement II alone:
C is facing the opposite direction of B. D is sitting to the second left of C. But we are not given any information about the direction of D.
Statement II alone is not sufficient.
Statements I and II together:

We cannot determine the direction in which D faces.
Hence, statements I and II together are not sufficient.