"I understand the funds from her share will automatically go to her husband"
No, you are wrong on this point.
You said that she died after your parents? If that is the case then it all depends if she had a will or died intestate (that means that she did not make a will).
If she had a will then the money will be distributed according to the will.
In that case, you will release the funds to whoever the executors of her will are.
If she died without making a will then the intestacy rules kick in. These differ between countries (eg if you're in Scotland then the rules are different from England & Wales).
Presuming that you're in England or Wales, then the first £322k of her estate goes to the husband and anything above this amount is split 50/50 between her husband and any children.
That's not just her inheritance from your parents but her total estate.
For example, if they owned their home as "joint tenants" then the family home passes to the husband regardless of any will and is not counted as part of her estate.
In contrast, if they owned the home as "tenants in common" then her separate 50% share of the family home is counted as part of her estate.
But, regardless of who gets what, if she died without making a will then whoever has been granted letters of administration then that is who you release the funds to.
In both cases you need to see the grant of probate before releasing funds.