I like the way you framed this question. There is no single right answer for what to do with your savings, but there are some choices that are wrong in the sense that they are dominated by other choices you could make. Of the choices you listed, there are two that fall into that category. The ones that seem like a bad idea to me are:
Putting it into your Roth 401(k). You can't do this directly anyhow, but you could do it indirectly by increasing your contributions and using the growth fund to cover the hole in your budget, but that's a lot of work for a relatively small gain. You would essentially be exchanging one long-term investment for another long-term investment. You would pay capital gains taxes on the investment when you sell it today, in order to not pay taxes on its earnings when you eventually withdraw it. There is some benefit there, but it's a long way off, not that large, and probably not worth the effort. Things that might change your mind: If your 401(k) was a traditional 401(k) (paying tax at capital gains rate today to get a deduction at your normal income rate is likely to be a win). You're not contributing enough to get the full company match (always try to get that match if you can).
Putting it into your emergency fund. Once again, you are likely to pay capital gains tax if you do this, and you will be putting it into an investment that is likely to get a lower return than your current one. It isn't really necessary to incur these costs, since if you encounter an emergency that you can't cover with your existing emergency fund, you could always liquidate the growth fund then, when you know you need it. Now, a growth fund is going to be more volatile than what you would normally want for an emergency fund, but the risk isn't that bad, if you think about it. Say your emergency comes up and you find that the growth fund is down 20% (which would be a pretty horrible run). That's $600 less that you have to deal with the situation. Keep in mind that you already have $2000 (and building) in your current emergency fund. Is that $600 going to make the difference between meeting the need and not? It's not likely. Better to leave the investment where it is and keep building your emergency fund week by week. Things that might change your mind: Your level of risk aversion (if having that money in a more risky investment is keeping you up at night, move it). You face significant job uncertainty (if you have reason to think your job is at risk, it might be a good idea to top off that emergency fund sooner rather than later.)
Your other two choices both seem like solid options under the right circumstances. If it were me, I'd leave the investment in place rather than use it to pay off the student loan. The investment is likely (though of course not guaranteed) to earn more than the interest rate even on the highest-rate loan, especially when you consider that the interest on the student loan is probably tax deductible. Moreover, the size of the investment isn't enough to fully repay the loan, so putting it toward the loan won't even improve your cash flow for some time to come. However, there is always a chance that the investment will perform poorly and some people prefer the guaranteed return from paying off the loan. It depends on your personal risk tolerance. The one thing I would recommend is to think of putting the money toward the loan not as a debt repayment, but as a fixed-income investment with a yield equal to your loan's interest rate. If you would still consider buying it then, then go ahead. If not, then stick with what you've got. In my experience people get way too emotional about debt; try to take that emotion out of your decision making if you can.
