My guess is they aren't being intentionally vague or evasive. They probably don't know/remember or haven't set anything up at all.
I took a look at your
investment options linked from the top of the plan providers section and it looks like you have a couple of decent options you could go with. None of them are perfect, but definitely workable, depending on what options you have elsewhere and what you desired asset allocation is.
NationwideVanguard Institutional Index (S&P 500) VIIIX 0.02%
Empower Retirement iShares U.S. Aggregate Bond Index BMOIX 0.10%
Vanguard Small Cap Index VSCIX 0.04%
AIG (formerly VALIC)Vanguard Total Stock Market Index VSMPX 0.02%
T. Rowe PriceT. Rowe Price Equity Index Trust (S&P 500) N/A 0.06%
VOYAVanguard Long Term Bond Index VBLLX 0.05%
VOYA US Stock Index Portfolio (S&P 500) INGIX 0.27%
Vanguard Mid-Cap Index2 VMCIX 0.24%
Vanguard Small Cap Value Index2 VSIIX 0.26%
Given these options I would probably go with AIG (formerly VALIC) as it offers a lower expense version of the oft recommended VTSAX. If you go with this you'll need to get any bond and international exposure elsewhere. My only hesitation here is that VALIC can be a little hard to deal with. My wife substitute taught for a district with a VALIC 457(b) and it was a bit of a pain to get it rolled out. It worked out in the end, but it required getting the district to sign off and we no longer lived there at that point. Not the end of the world, just something to keep in mind if you leave this employer.
If you wanted to get both stock and bonds in your 457 you could go with VOYA, but you'd have to do more work get the stock funds to sum up to the total market.
I didn't see any good (low expense) international investment options, so you'll need to get that elsewhere if you want. Your 403(b), an IRA, or a taxable account would all be possibilities.
Back on the the
main plan page it says you can invest at Schwab with "Enrollment available through Nationwide," so you could find out what investment options that opens up and any other details. I would only both with that if you need to get bond and international investments in your 457(b). If you can get those in other accounts I would just go with AIG (formerly VALIC).
I actually just found the
full FAQ which has a question "What funds in the Plan have the lowest fees?", the response to which pretty much mirrors what I wrote above, so that's pretty cool of them. You might find other good information in that FAQ.
In that FAQ I see that investing with Schwab costs $25 per year and appears to give you access to a full brokerage. You should confirm details, but given that Schwab tends to have good low expense index mutual funds and ETFs that trade commission free, I would say this is probably a good option if all your investing will be through your 457(b), but I'd probably stick with my AIG recommendation if you have other accounts.