Anytime that you are combining two simple sentences to write one complex sentence it will have a subordinate conjunction is this correct.
Example> The Lydians began the use of money in 700 B.C.before they invented coins.
The first sentence was The Lydians began the use of money in 700 B.C. They invented coins.
A) Don't run around.
B)after the store don't run around.
C)after the store.
Yes, you are correct. Anytime you combine two simple sentences to create a complex sentence, you will usually need to include a subordinate conjunction. A subordinate conjunction is a word that connects the dependent clause (subordinate clause) to the independent clause. In the example you provided, the subordinate conjunction is "before." By using the subordinate conjunction "before," you are able to join the two simple sentences into one complex sentence.
