"Underlying these and other attempts to change the subject there was a deep-seated hatred."
"Underlying these and other attempts to change the subject was a deep-seated hatred."
Are these sentences both correct?
Yes. I think the 'there was' version may be very slightly more common in speech - to make the sentence easier to parse (as Underlying and deep-seated hatred are so far apart (and 'there was' is more obviously related to 'underlying;). But either is fine.
b