If OP wife has an NI number he can call the Department of Work and Pensions (DWP) to find out whether she has any NI contributions on record.
She needs 10 years of contributions to get any UK pension at all. At present it is possible to buy up to 6 years of NI contributions. The rate is 17.45 pounds per week, so about 900 pounds for each year.
DWP will want to know her work history and addresses whilst in the UK. My experience of contacting the DWP has always been positive, helpful and friendly.
If the wife was on a low wage or claiming benefits while in the UK she may have been given NI credits, so it's worth checking.
Married pensions and spouse pensions were stopped years ago, so a woman can't use her husbands NI contributions to get a pension - except people who qualify for the old basic pension (women born before 1953 and men born before 1951 ?not sure of the year?).
10 years of contributions would get 10/35ths of the full state pension. That would be 58 quid a week, just over 3,000 quid a year.