Hello Optimus
B and C put the emphasis on 'spending some time with her'. The split infinitive in C gives an impression of 'sudden self-interruption', as of a sudden realization. A puts the emphasis on 'hating her guts'.
Let's say I'm talking to my son about his mother, who has run off with the chap who came to install some double glazing.
Sentence A suggests that 'hating her guts' is understandable, but nonetheless, he'd better spend some time with her. Sentences B and C suggest that 'spending some time with her' is the right thing to do; the 'hating her guts' is acknowledged, but made to seem less important.
By the way, if you're having any double glazing installed, watch out for a big burly chap with a white van. The *^£%^+>.
MrP