  We explore a simplest viable dark matter model with a real singlet scalar,
vector-like singlet and doublet fermions. The Yukawa coupling associate with
the fermion sector play a crucial role to get the current relic density of the
Universe through Freeze-in and Freeze-out mechanism. We propose a solution to
muon anomalous magnetic moment in an economical fashion via the dark matter and
fermion doublet interaction. We discuss the constraints from the recent muon
anomalous magnetic moment experimental data and relic density. We also perform
the collider analysis for the FIMP dark matter in the context of 14 TeV LHC
experiments with the MATHUSLA100/200 detector. We find that one can get enough
events $>3$ for heavy charged fermion track at 14 TeV LHC with an integrated
luminosity $\mathcal{L}=10^6 ~{\rm fb^{-1}}$.
