You don't seem to understand the attitude/perspective of the US Consul.
They quite easily may be thinking that she is trying to get around the system.
Talk to an attorney about how she can better prepare a tourist visa application ... a letter of invitation has almost zero value.
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214(b) means they did not think she would return home.
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They suspect she is going to come to the US and stay. The fact that her husband can sponsor her supports their suspicion since they likely think that she is trying to get around the proper procedure at the embassy. You need an attorney to help you overcome their suspicion.
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