"The trust or benes?"
If there is sufficient state source income, then it could very well be both who must file.
State requirements vary so I have included links (below) to each state mentioned in your post.
ND: https://www.nd.gov/tax/user/businesses/formspublications/fiduciary-tax
MN: https://www.revenue.state.mn.us/Forms_and_Instructions/m2_inst_18.pdf
MT: https://mtrevenue.gov/taxes/fiduciaries/filing-requirements/
