A CIT is a “collective investment trust” — created for investors inside a 40l(k) plan. They are said to have lower fees than mutual funds typically included inside a retirement plan. BUT, they also have far less disclosure of their investments, since they are not covered by the “Investment Act of 1940” which governs mutual funds. You can read more about CITs in this article from Investopedia.
My advice, given your age and stage of life — and what I see in the stock market — is that you should use the Vanguard Balanced Index Fund because I can’t imagine anything less expensive in your fund choices. BUT ALSO, since you are so close to retirement, and since (read next week’s column at my website), the stock market has made such tremendous and unprecedented gains, I think you might want to take about 25 percent of your account and put it into the safest alternative (not bonds!) such as a “stable value” option or a money market fund, if one is included in your plan. You don’t want a bear market to wipe out those nice gains.