A. Hardly had Tom the house reached, it started to snow heavily.
B. Hardly Tom had reached the house, it started to snow heavily.
C. Hardly had Tom reached the house, it started to snow heavily.
Feedback If 'hardly' goes in the beginning of the sentence we should invert subject and predicate. Compare: Tom had reached (normal word order) - had Tom reached (inverted order)
D. Hardly had reached the house Tom, it started to snow heavily.