7 year rule and failed pet

[Nicklam]

Just a question i wanted answering for my knowledge

Suppose say father makes a part gift of our house valued 800k to me which we live in, and 4 years later he passed away. This is a failed pet and we will be taxed for iht from his nil rate band at 325k accordingly on the failed pet.
But can he use my mothers TNRB and both the RNRB? Or is it only his NRB that will be available on a failed pet if he was to pass?

[Nicklam]

Just to add to the above
Mother passed in 2012 left everything to husband.

Father later gifts part of house to child jointly. They live together. 4 years later father passes.
On the failed pet or grob, not sure which applies but can motheres TNRB and RNRB also be used at time of fathers death?

Full value of property is 800k
Father also has 250k cash in bank