Answer
Yes. Fissionable by thermal neutron.
Work Step by Step
When nuclear fission occurs, an atom splits into two atoms and release energy. The energy produced by this fission is 5.0 MeV while the nuclide $^{237}Np$ only require 4.2 MeV for the fission.
Hence the $^{237}Np$ is fissionable by thermal neutrons.