What constitutes humanitarian reason for expedited immigration?

Instead of looking for sufficient situations that qualify, you should discuss how your own situation can build an expedite request. You will need to submit evidence of your reasons. Expedite requests are granted, rarely. You will want to consult an attorney for help if this is how you want to proceed.

If you are doing the USCIS I-130 and NVC I-864, to be followed by a Consular DS-260 ... I need to be honest .. they almost never grant humanitarian expedites. In 30 years, I only saw one ... the US citizen husband that was in the US had cancer and needed surgery. Thus, in my opinion, your reasons need to be similarly 'strong.' Sorry PS You should consider consulting with an attorney, to have him/her help with the papers so that there aren't any unnecessary delays due to you not understanding the instructions/process.