Immigration documents of friend

I got a message from my friend the other day on my social media account. She has been very busy on the processing of the immigration documents of her foreigner husband. They had been here in the country for almost four years already and she wanted that her husband be permanently resident so that they will have no hassle anymore with regards to his staying here in the country. One of her request for me is the affidavit of cohabitation stating their marriage date and address where they live. A statement of being married as husband and wife together with their length of stay.