I think most people who hold the Bible as a sacred text would not consider "concluding" a chapter of any portion of the Bible in a way other than how the original manuscripts have been written and translated. Because they are considered to be inspired by God, altering that text is inconceivable.
So I'm going to assume that the question really needs to be interpreted in one of two ways.
First, the book of Mark originally contained only eight verses in the final chapter. Mark himself ended chapter 16 with
Trembling and bewildered, the women went out and fled from the tomb. They said nothing to anyone, because they were afraid.
Perhaps three hundred years later (the dating is debatable), additional verses were added to this chapter, noting the appearance of Christ to Mary Magdalene following his resurrection and then later to His disciples. So perhaps your question is really asking where the Gospel of Mark should end (or conclude). Should we consider the book complete after verse 8? Or are verses 9–20 also biblically significant and also inspired by God? That's a deep theological debate you'll have to work out for yourself.
Or the question could be asking something along the lines of what you personally can conclude from Mark's writings. Why is this book important? Why is it important that this Gospel was written first and not long after the death and resurrection of Christ? How does the example of Christ instruct Christians today—thousands of years later and in a vastly different society—in living their own lives? How does Christ treat others, and why is that significant?
I hope that in knowing your instructor and having more information about class discussions and readings, these analyses of the question you posed will help guide you toward a meaningful and personal response.