Ginzan Onsen evening transportation

I am planning to go to Ginzan Onsen at the end of January but all accommodations are full already, so all I can do is a day trip, but I want to take the evening photos, buses finish pretty early, I think the last bus is about 6:00pm, is the bus schedule stable? I am worrying if I missed the last bus, or the bus is cancelled for some reason, I will choose taxi as a backup, is it easy to catch taxi there back to Shinkansen station? I can't speak Japanese so it is very hard for me to book a taxi. I am also thinking about renting a car but worry about the heavy snow on roads, I have only tiny experience to drive on snow, is it safe to do so? Is there any other options?

It s a bit funny but really worry if I can't get back to train station, I will need stay on the street under snow overnight

I've never been there, so I don't know the details.
If you have never driven on a snowy road, I do not recommend driving.
You can contact the taxi company here. (Obanazawa Taxi)
http://www.obanazawataxi.net/call_taxi/
http://www.obanazawataxi.net/
https://www.taxisite.com/cal/profile/1981.aspx
Taxi fare: Oishida Station to Ginzan Onsen, small 4-seater, 5,300 yen, but there is a possibility that it will fluctuate slightly.
https://www.obane-kankou.jp/%E3%82%A2%E3%82%AF%E3%82%BB%E3%82%B9/
The bus from Ginzan Onsen is scheduled to depart at 18:21, but the schedule may be disrupted due to bad weather.
http://www.hanagasa-bus-taisei.co.jp/base.html

@Kalawuf
By 17:00 , very likely ealier, all the street ligntings will be on, you will have at least one hour to take photos, and catch your bus at 18:21. If you are planning to stay longer, just prebook a taxi at a scheduled time. Hopefully, it is snowing during your visit. Enjoy the trip!

I can't speak Japanese, pre-booking taxi by phone call is very hard for me, and can't find any taxi app that covers Yamagata, that's my main concern

You haven't seen the page I linked to.
The e-mail address is written here, so please check it in advance.
http://www.obanazawataxi.net/call_taxi/
It says here that it is also available in English. However, I don't know how many staff can speak English.
(Please use translation software to read)
https://www.taxisite.com/cal/profile/1981.aspx
In google translate, voice translation function and alphabetical notation are displayed.
For example, I'd like a taxi please
タクシーをお願いします（Takushī o onegaishimasu）
is displayed.

I can't speak Japanese

No problem, just go to the Tourist information centre, 2 minute walk from Fujiya Ryokan, and the lady in the office will book a taxi for you. If the office is closed, visit the reception of the Fujiya Ryokan, most of the staff there speak perfect English, and will definitely assist you in booking a taxi.

Thanks everyone, very helpful information, although I have been to Japan several times, but this time is in heavy snow season, just worried if I have been trapped there without accomodations, will have stay overnight under snow, haha

End of January sunset will be around 17:00. Ginzan onsen is small. So if the bus only is at 18:00 you have quite some time for pictures

@Kalawuf
How was your expreience in the end? I'll have exactly the same situation as yours. Was that hard to get on the bus? Or you took a taxi? Was it difficult to get a taxi on spot? Thanks in advance for your sharing.

Hi. I have just been to Ginzan Onsen on Thursday last week and there were too many people to fit on the last bus unfortunately.
I did a share with a couple of other travellers and it cost us about 1700Yen each and there were taxis waiting at the bus depot so it wasn’t hard to get back to Oishida.