No, Henna does not have any liability. She did not actually steal any money, and she did not even attempt to steal any money. She simply thought about it, but then she decided not to do it.
In the eyes of the law, Henna did not commit any crime. She did not have the requisite mens rea, or criminal intent, to commit theft. She did not intend to steal any money, and she did not take any steps to steal any money.
Henna's actions were simply a thought crime, and thought crimes are not illegal. Everyone has thoughts that they would never act on, and Henna is no different. She should not be punished for something that she only thought about doing.
Henna's actions were also not unethical. She was tempted to steal money, but she ultimately decided not to do it. She showed good character by resisting temptation and doing the right thing.