Confirmation process


Hello. Trying to get to grip with complexities of the confirmation process.
Can I please check with this group if my interpretation of the pertaining IHT rules for grant of confirmation of my mother in laws estate, and forms to be completed, are correct. She died Jan 2023.
The value of her estate is roughly £680,000
(Property value c£360,000 and bank/investments of £320,000)
She has available to be transferred to her estate her husband’s entire £325000 NRB (he died some 20 years ago.) to be added to her own £325,000 NRB allowance.
In addition, there is 100% of RNRB of £175000 x 2 - available to be added - she is leaving her property , wholly passed to her on her husband’s death to her 2 children.
Is it correct that based on above, her estate is classed as exempt?
Am I also right that as no IHT is therefore due, only form C1 requires to be completed for confirmation?
Am hoping my reading of this is right, but will appreciate knowing if any of above is off track.
Thanks in advance for any input.
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