Condolence on your husband's passing. Off the top of my head, I believe you do have to have file 1042 and related forms. Do take a look at the U.S.-Canadian Tax Treaty, the tax rate may be limited to 10%.
You mentioned Income with Respect of a Decedent of $260. So I assume that's just the unpaid accrued income earned before his death. If the annual income is still rather small, it may be more troublesome than its worth. Has your son considered disclaiming the inheritance? However, a qualified disclaimer must be declared in writing within 9 months from date of death.
