Two of the most frequent locutions with “-grubbing” are “money-grubbing” and “penny-grubbing,” in the senses of avaricious and miserly.
“goblin” in the sense of Kobold, used of an upstart, parvenu, etc., makes exceptionally little sense.
So does the word maybe have another meaning? In fact it does. OED lists “goblin” in the sense above: a sovereign (21 shillings, i.e., 1 pound and 1 shilling).
Your author is trying to convey some historical 19C flavor and instead of “sovereign-grubbing” writes “g.-grubbing.” The sense? A mix of avaricious and miserly.
(Incidentally, the alternative terms listed by OED [“Jimmy O’Goblin” and “O’Goblin”] were apparently still being used well into the 20C—last noted use 1973 for the former, 1925 for the latter [courtesy OED]. I’d never come across any of them before though.)