  Recently, Ising superconductors which possess in-plane upper critical fields
much larger than the Pauli limit field are under intense experimental study.
Many monolayer or few layer transition metal dichalcogenides are shown to be
Ising superconductors. In this work, we show that in a wide range of
experimentally accessible regimes where the in-plane magnetic field is higher
than the Pauli limit field but lower than $H_{c2}$, a 2H-structure monolayer
NbSe$_2$ or simiarly TaS$_2$ becomes a nodal topological superconductor. The
bulk nodal points appear on the $\Gamma- M$ lines of the Brillouin zone where
the Ising SOC vanishes. The nodal points are connected by Majorana flat bands,
similar to the Weyl points being connected by surface Fermi arcs in Weyl
semimetals. The Majorana flat bands are associated with a large number of zero
energy Majorana fermion edge modes which induce spin-triplet Cooper pairs. This
work demonstrates an experimentally feasible way to realise Majorana fermions
in nodal topological superconductor, without any fining tuning of experimental
parameters.
