In elderly women, i.e., postmenopausal ladies; it is not so common to have thrush (fungal infection). This is because; the fungus causing thrush needs acidic environment to grow. This milieu is mainly enhanced, if the woman is taking oestrogen based hormone replacement treatment (HRT).
As the thrush causing fungus needs oestrogens to thrive, sometimes it is worthwhile to stop HRT for a short term and take anti thrush medications and apply anti-thrush ointment in the genital area affected.
By doing this, if oestrogen was a stimulus and if it is taken away by stopping it, then symptoms of genital itching should subside.
If symptoms still persist, then an expert input would be advisable