This is more of an economics question than pension law
If she wasnt allowed to draw her pension before her 60th birthday then again it is a question of pension contract and not law
if she was - then there would be adjustment down for drawing it 'early' and she would be better advised to wait three months - perhaps she was.
NHS pension for example the adjust ment would be six months pensions worth.
There is one figure of twenty five thou and one of two hundred and fifty thou. Can I assume one is a typo ? ( but which )
and finally her lump sum should not be taxed ( or have I missed an imortant change in pension law ?)
Now suppose in Feb she would have got £100
and now in May at the time she vested she got £90
does she have a decent claim for £10 ?
now THAT is a law question
and my opinion is I think not because the advice in Feb was not osbviously negligent.
( NB not a lawyer but used to do pensions informally )