For a defamation claim, you also need an unprivileged publication to a third party.
Even if it were assumed to be "an attempt to cause distress for the tenant", that alone would fall far short of what it takes to constitute an IIED claim. Issuing a notice to quit premised upon the representation that a tenant is hording is not the type of conduct that is going to be regarded as "outrageous" or that "exceeds all bounds of that usually tolerated in a civilized community" nor is it the type of conduct that would foreseeably result in severe or extreme emotional distress. Nor, for that matter, is there any allegation that severe emotional distress resulted.
Even after clean-up, the OP states that following a clean-up by the tenants, "Hoarding not present, and if it did exist it was no less than or equal than one on a scale of ten.", so we have a tacit admission from the OP that this was fairly characterized as hoarding, albeit minor hoarding. Prior to the clean-up, it's reasonable to infer that the situation was considerably worse.

