Exoplanets hosting M dwarfs are the best targets to characterize Earth-like or super-Earth planetary atmospheres with the James Webb Space Telescope (JWST). We determine detailed stellar parameters ( Teff, log g, and ξ) and individual abundances of twelve elements for four cool M dwarfs hosting exoplanets TOI-1685, GJ 436, GJ 3470, and TOI-2445, scheduled for future observations by the JWST. The analysis utilizes high-resolution near-infrared spectra from the SDSS-IV APOGEE survey between 1.51-1.69 µm. Based on 1D-LTE plane-parallel models, we find that TOI-2445 is slightly metal-po or ([Fe/H1 =-0.16 ±0.09), while TOI-1685, GJ 436 and GJ 3470 are more metal-rich ([Fe/H1 = 0.06 ±0.18, 0.10 ±0.20 dex, 0.25 ±0.15). The derived C/O ratios for TOI-2445, TOI-1685, GJ 436, and GJ 3470 are 0.526 ±0.027, 0.558 ±0.097, 0.561 ±0.029, and 0.638 ±0.015, respectively. From results for 28 M dwarfs analyzed homogeneously from APOGEE spectra, we find exoplanet-hosting M dwarfs exhibit a C/O abundance ratio approximately 0.01 to 0.05 higher than those with non-detected exoplanets, at limits of a statistically significant offset. A linear regression of [Fe/H1 vs. C/O distribution reveals a noticeable difference in the angular coefficient between FGK dwarfs (0.27) and M dwarfs (0.13). Assuming our abundance ratios of Ca/Mg, Si/Mg, Al/Mg, and Fe/Mg, we determine a mass of 3.276−0.419 +0.448 M⊕ for TOI-2445 b, having density (6.793−0.099 +0.005 g.cm − 3 ) and core mass fraction (0.329−0.049 +0.028 ) very similar to Earth’s. We also present an atlas of 113 well-defined spectral lines to analyze M dwarfs in the Hband and a comprehensive evaluation of uncertainties from variations in the atmospheric parameters, signal-to-noise, and pseudo-continuum.