> What should my b, c, n values be?

See details here (~4/5 down on the page):

[afni.nimh.nih.gov]

Basically these parameters will decide the beginning (b) and end (c) of the HRF, and number (n) of basis functions. Usually you set b=0 unless you believe there is anticipation or delay going on. Setting c and n will depend on your specific experiment type.

> Would this command run correctly with the given files (attached).

Looks fine to me. You don't have to, but you may scale your original EPI signal be the voxel-wise mean so that the resultant betas can be interpreted as percent signal change.

> Would the output be the correct 1D graph of a HRF?

I think so.

HTH,
Gang