  The primordial heavy or superheavy dark matter that could be created during
the reheating or preheating stage of the Universe can undergo QCD cascade decay
process to produce leptons or $\gamma$ as end products. Although these could be
rare decays, the energy involved in such decay process can influence 21-cm
signal of hyperfine transition of neutral hydrogen during the reionization era.
We explore in this work, possible multimessenger signals of such heavy dark
matter decays. One of which could be the source of ultra high energy neutrino
(of $\sim$ PeV energy regime) signals at IceCube detector whereas the other
signal attributes to the cooling/heating of the baryons by the exchange of
energy involved in this decay process and its consequent influence on 21-cm
signal. The effect of evaporation of primordial black holes and baryon
scattering with light cold dark matter are also included in relation to the
evolution of the 21-cm signal temperature and their influence are also
discussed.
