I think more likely IR 168. This series of photos was taken on the occasion of the Grand Duke‘s visit to the 25.Reserve-Division on 24 January 1916. IR 118 was in 56. Infanterie-Division. The general officer with the pour le mérite is Kuno von Steuben, commanding XVIII. Reserve-Korps. The Hessen-Darmstadt digital archives site actually shows the same occasion captioned as a visit to RIR 83 (same brigade as IR 168).
Regards
Glenn