Non reply of show cause notice

I think, you can go under rescue of section 80 of Finance Act 1994 "Penalty Not to be imposed in certain cases"

Plain reading of section is " Notwithstanding anything contained in the provisions of section 76, section 77 or first proviso to sub - section (1) of section 78, no penalty shall be imposable on the assessee for any failure referred to in the said provisions if the assessee proves that there was reasonable cause for the said failure.

Concluding, i wish to mention that by referring this section you can give the acceptable reason.

Thanks