The correct answer is the third sentence: “We had a heavy hot meal and soon wanted warm snuggly naps.”
In this particular sentence a comma is not needed as the coordinating conjunction “and” joins an independent clause (“We had a heavy hot meal”) and a phrase which is not a complete clause; that is to say, it has not subject and verb, and it does not convey a complete thought (“soon wanted warm, snuggly naps.”)