Bleek Emmanuel Ja

No way to tell. Depends on the consular officer and what questions he/she may ask. But hopefully it will be smoother than the first time

Yes you will have to go for a second interview, as USCIS doesn’t issue visas, only the consulate does, so you will have to go to another interview and hope that this time the consular officer approves the visa

Thank you for your message okay. We have being talking to the USCIS about this case and they confirm to us that the waiting period is just 3 months for the review and it will be reaffirm back to the consular, please do not reply message the way you sound . you are making me feel more bad about it . thank you . my question is this , after the reaffirm and the case is send back here , would they be any delay again?  Am in Nigeria

I am frankly shocked, that your new wife didn't end up with a RFE, if the death certificate wasn't loaded into the petition from start.
 
and there is a list of all things that are required to take to interview.
 
at this point your wife can contact NVC and talk to them ask them to look at the notes on the account to see the exact status if they will tell her.
 
I would venture to say your wife will need to show proof of bonafide marriage, there was something the CO didn't like and the reason it was sent back to NVC, and ultimately USCIS, I would recommend having her speak to an immigration attorney at this point if things have not been understood what is need from start which is what it sounds like.

I want to thank every one that as giving me good encouragement and instructions how to prepare for my cr1. My interview was held early this morning and it was successful.  I really thank God. 

First application was a K1 / they could not appeal
 
we need to know what country / embassy you will go to
very important
and yes,  most of the time the age difference is an issue and may require several applicaitons and proof to get a visa approved 
you need several visits for many embassies to approve like ours
all i can suggest for this interview is to be well prepared / some embassies don't look at the emails or chats / they look at your honesty
quick response to simple questions like "what is her favorite color?" / they can ask the stupidest of questions like they asked my husband what color was my carpet / he did know i just put in hardwood floors 
be confident that you know her well 
be prepared to show love and be responsible for her feelings
know what future plans you have like will you study or work here in the USA

He is in China. And i just got back from China. I file my I130 in April. And I still did not receive approval letter. I wish my husband can care bout our case just like you care about yours. I mean he does care. But He knows nothing about immigration. I went to China 5 time in 2 years. Since i am s student. And i know how hard it is to live separate from spouse. It affects me a lot. Every time i came back from China. I will book my next flight immediately. I can't image if I were you, 6 years. It's a long time and I hope CO can understand it too. I really want to ask them how many 6 year does someone have in life. 
 
Best wishes for you
Do your part and God will does the rest. 

Age is not the issue, validity of the relationship is.