Was Marie Antoinette's death reasonable. Could their have been any harm in sending her home?

Very little of the violence of the French (or any other) Revolution was reasonable. However, it was seen as necessary by the Revolutionaries, who wanted to be as sure as possible that they had got rid of any possibility of the Royal Family regaining power.

I don't believe it was, the Revolutionaries simply wanted blood. They saw Marie Antoinette as an enemy of the republic and as an enemy of the Republic she should be treated as how all enemies of the republic were treated, by being executed. You have to understand she was hated more than any other Queen of France had ever been, there was a point when they debated deporting her back to Austria, however, in doing this her and Louis could have come back with foreign allied troops and reconquered France with the help of her bother the Austrian Emperor Joseph II. But due to the beginning of The Reign of Terror, the principles of the French Republic was that everyone (even a former King and Queen) should be treated like everyone else. This ultimately resulted in them both being executed along with thousands of others during the reign of terror (its important to note, at the peak of the Reign of Terror they were executing around 600 people a month). Louis XVI's advisors tried to get them both to leave France when they were still at Versailles, but Louis did not want to risk being a "fugitive king." After he had decided this (which is a miracle he even decided considering he had a reputation for never being able to come to a decision on anything) Marie Antoinette saw it as her duty to stay at her husbands side and give him all her support.

no... it was vengance. vengance is never a good thing... but aristocracy causes masses to suffer for the few to live in lavish luxury... the epitome of selfishness... I know I won't shed any tears over the deaths of our modern economic slavers... and I am far more forgiving than most people.