General Buhari

All consulates offer DCF with exceptional circumstances. 

I'm not sure where you are getting this information. The website you have been copying and pasting from earlier (https://www.ustraveldocs.com/ng/ng-iv-visaapplyinfo.html#) clearly states:
@General Buhari, I would try to contact the Lagos Consulate and ask if they will accept your Direct Consular Filing. Be sure to clarify that you are a US Citizen, that you have been a legal resident in Nigeria for years, and that you and your wife need to return to the US for a medical emergency. It would definitely help if you have been filing your taxes in the US these past years, and if you have done other things to maintain your domicile (back accounts etc). Hopefully they will be able to give you an updated list of the required documents, because the list on the website seems outdated.

Thanks everyone for your responses. I’ll open a thread in the DCF forum for further questions.

Thailand.  Don’t know how hard it will be for a Nigerian to get a visa.   But the health care is superb. When you enter a private hospital there it is like you have been teleported into a Jetsons episode.  

https://travel.state.gov/content/travel/en/us-visas/visa-information-resources/forms/ds-160-online-nonimmigrant-visa-application/ds-160-faqs.html
 
 The online DS-160 application replaced the DS-156, DS-157, DS-158, and DS-3032, which are no longer necessary

Another B application would need another Emergency Appointment to meet your timeline and I do not know if that can be done.

This is different.  "My wife is my primary care provider because I can not function as a recent paraplegic."   The OP is not currently inside the US.

The rules for domestic servant of a U.S. citizen don’t completely apply to OP. Otherwise I would have suggested a B-1. 
 
https://web.archive.org/web/20190217030313/https://mx.usembassy.gov/visas/domestic-employees/
 
Personal or domestic servants who are accompanying or following to join their United States citizen employer in the United States may be eligible for the B-1 visa classification if:
The American Citizen ordinarily resides outside the United States and is traveling to the United States temporarily. The American Citizen’s employer is subject to frequent international transfers lasting two years or more and who, as a condition of employment, is going to reside in the United States for a stay not to exceed four years The emboldened above does not align with OP’s situation. Sadly Congress makes it easier for an alien on a non immigrant visa or status to bring a domestic servant than it does for a U.S. citizen.  
 
Thus  I agree with @JeanneAdil

He needs assistance traveling to the US.  

I doubt that is the issue, more likely that they think she will stay and adjust.

I was able to secure an emergency appointment.

She can apply again, but I would not rate her chance of obtaining a visa high.

I am sorry that you are experiencing this.  Have you written to the consulate and explained the entire situation?  I find it strange that the consulate would deny the B2 based on these circumstances.  Perhaps you US Senator could provide some help.

100k-130k naira 

Can Anyone please give me the  medical Exam cost.in Lagos Nigeria For 2018 Thank you and God Bless I've heard so many Prices and I'm Not falling for Scams .
 
 

I have flown over countries I would not want to get a visa for.

Good   It will stop a lot of immigration silliness that is going on now. 

I'm willing to bet she did.

I agree. In her home country she wouldn't have moved across the street for a man who shows no interest in her, peppers his Facebook page with pictures of other women, cheats on her, doesn't let her know where he is....yet when a green card is brought into the mix people will put up with anything. It's quite sad, really. 

agree
many of the officers ask what address are you going to and check that with the packet
how did this cousing know to pick her up
don't forget the poot guy from Atlanta whose gf sent message in airport saying POE was sending her back and then the guy saw her leaving in another car
not knowing where he lived doesn't make sense

she didn't have husband's address 
that is on all the documents,  application,  letter of support and everything
also on the outside of the packet she gives to POE officer
this does not make sense
we would need the real story to advise

The purpose of a green card is to reside/live in the US.  She cannot stay in the US for only a month or so every two years.  She will find herself out of a green card pretty quickly if she tried to do that, and could be placed in deportation/removal proceedings.
 
If she wants to live outside of the US and just visit for only a month or so every two years, then a tourist visa (B1/B2 visa) is what you need to apply for.
 

But it may not be so much longer if her family comes. Lesser stressors have broken up many marriages.

Apparently a lot happened in those two days so it wouldn’t be beyond the realm of possibility that she did 😊 lol