Expired IELTS certificate for naturalization application

Hi
I have searched and found multiple topics but nothing is new and conclusive.
So here is scenario.

-My wife entered into this country as my dependent and has ILR as of last year. At the time of her first application, we presented her IELTS certificate with her application although it was not required at that time. She applied for dependent visa from Asian country and was granted a dependent visa of work permit holder (which was me). This IELTS is EXPIRED now.
-She had to give IELTS language test again in order to get registered with health professional council in the past. She appeared in IELTS here in UK and scored enough to get registered with health professional council. This second IELTs certificate was never present to home office during her extension application or ILR application. This IELTS is EXPIRED now.
-She has given life in UK test last year.
-She applied for ILR in OCTOBER 2013 under old rules and was granted ILR alongside me.
-We tried to ring home office to get clarification but despite of multiple attempts nobody responded.
-My wife spoke to NCS office today and lady was not sure.
-We have sent this question to home office and we have given pre- defined answer which does not really answer the question. It talks about everything else than what we asked.

Now as she is applying for naturalization and we wonder if we can use any of those IELTS certificates with her Naturalization application?
or Does she has to go for a different language requirement test again?

Many thanks.

According to this link on gov uk website, IELTS validity is 2 years, I'd have her sit B1 exam just to be on safe side.