If martial law is declared, then government powers are almost unlimited, with most or all of the normal legal system suspended.

Under such conditions, it would in general be best to follow the directions of the government, which will likely be enforced by the armed forces as well the police.

Remember that disobeying instructions under martial law is likely to result in imprisonment, perhaps in conditions much harsher than would normally be allowed, or even in being shot.

If you decide not to follow emergency instructions, then remember that this is likely to be a very high risk strategy.
Enforcement is likely to be stricter in urban areas. TPTB CAN patrol densely occupied areas very thoroughly and shoot violators
Out in the countryside, there are simply not enough troops to patrol everywhere, though remember that a variety of surveillance techniques allow a small force to observe a large area.

Also under martial law, TPTB can confiscate firearms, food, fuel, precious metals, real estate, and anything else considered useful.

Any last minute or half hearted efforts to conceal supplies are unlikely to succeed and may result in summary execution.

It might be worth thoroughly concealing a stash of vital supplies well in advance, like now.
A deeply buried large plastic barrel containing long life supplies might be prudent.
If RECENTLY buried it might be readily detected, but after a year or two, the concealment should be effective.