  In this paper, we investigated the Fe K-shell lines in the supernova remnant
W51C and hard X-ray sources in the proximity. We measured the intensities of Fe
I K$\alpha$ and Fe XXV He$\alpha$ lines at 6.40 keV and 6.68 keV, respectively,
and found that the intensity of the 6.68 keV line is consistent with the
background level expected from previous studies, while that of the 6.40 keV
line is higher at the significance level of 2.0${\sigma}$. Given the presence
of gamma-ray emission and high ionization rate point spatially coincident with
the remnant, we conclude that the enhanced 6.40 keV line most likely originates
from the interaction between low-energy cosmic rays and molecular clouds. Also,
we discovered an enhanced 6.68 keV line emission from the compact H II region
G49.0-0.3 at the significance level of 3.4${\sigma}$. Spectral analysis
revealed that the temperature and abundance of the thermal plasma with the 6.68
keV line is $kT = 3.0^{+0.8}_{-0.7}$ keV and $Z = 0.5 \pm 0.2$ solar,
respectively. These values are explained by the thermal plasma generated by the
stellar winds of O stars.
