Minouchka

The sponsoring spouse can enlist a secondary co-sponsor (a person outside the household) who is willing to accept full financial responsibility for the spouse who is seeking the green card. This secondary co-sponsor must submit their own Affidavit of Support (Form I-864) and must meet the above income requirements all on their own. (In other words, there can be no pooling of income or assets between the sponsoring spouse’s household and the secondary co-sponsor.)

Have you been billed for the 2 fees online?
if so, after the payment is received, fthey direct u to fill these forms out online
then print them out for your own records
all is done online now

I believe that you did not need to send a copy of DS 260. Your beneficary need a copy of the last page of DS 260 to interview

you asked about social security / you mean IRS
tell him to go to nearest office as a walk in and when your turn comes up, they will give you a transcript / needs ID and SS card / do not send in as the forms are done online and documetns get lost / wait for NVC to tell you
he will fill out the I 864 online after paying the online fee
then bill for visa application fee and fill out that online
NVC will then tell him what is needed as Morocco embassy requires more evidence than other embassies
you will (they can email this and it is best way to get things fast) a list of what NVC needs examples like the 2 criminal investigation reports, years of tax returns they need,  and any other / this letter of instrucations will have a bar code sheet 
return it with all of the documents (1 mailing) and but the NVC case # CSBxxxxxxxxxx , both names and both DOB's on the upper right hand corner of EACH and 
EVERY page of all documetns / papers get lost in these offices
when case is complete, it is sent to embassy with a date of interview
now, NVC will tell you what documents to bring to interview and list of doctors for medical exam

You only need to include a copy of the latest return or transcript. It doesn't hurt to include all three if you have them.
NVC doesn't care that you filed late, only that you filed. Whatever's on the tax transcript is okay.
I don't believe you can get one over the phone - you can always call and ask, of course, but expect to get it by mail. You don't need the earnings statement for I-864, though - the latest tax return/transcript should be sufficient.

An I-864 from him and and I-864 from Mom.  That way, HE is not counted in Mom's household, and she is not counted in his.  Even if people live in the same house, unless they need to COMBINE income to qualify, nobody is a "household member" in the immigration context unless they are on a joint tax return or claimed as a dependent.

3 persons if it is just going to  be you and him and his mom in the house
He should have made out tax statements for the years he worked out of the country (he is exempt from owing them well over $100,00) so if under that amount he will not owe any back taxes)   if he already filed then he will need to send in copy of the IRS transcripts to NVC when asked to produce them
If his mom is older and retired or getting SS money, there is a different way to do the I 864 supporting documents
so, let us know here what further questions you or husband have
incha allah all will be good
household income for 3 must be $25,525