I do believe that the wife of the Orlando nightclub shooter should be arrested. Lying about her knowledge of her husband's plans to commit such an atrocious crime is an obstruction of justice. She should be held accountable for her actions and unwillingness to comply with the law, and be punished accordingly.
If the woman helped in some way, she should certainly be punished. It seems that there is some evidence that she lied about her cooperation and willingness to assist her husband, and they need to make sure to investigate properly and render sufficient and proper discipline for her part in the heinous crime.
No, the wife should not be punished for something her husband did, unless she was complicit. If she did not know what was going to happen, or had nothing whatsoever to do with the attacks, then she should not be punished. However, if she helped her husband plan or carry out the attacks, then she would need to be tried, too.
Obviously I haven't seen all the evidence in this case, but there's no reason to arrest her simply because of who she was married to. If there is actual evidence tying her to the case, for example if she helped plan the attack, then she should be arrested based on that evidence. Otherwise she's only guilty by association.