Hi

Once the completion of 56 days, she would need to leave the country. So I guess it's better to get the 3 month visa.

The for 3 month visa (it is called the visit visa. Not Tourist visa)
the procedures remains the same except that the form is different and you would need a letter from your sponsor. But as mentioned there is NO reason for them to reject the visa.
Hope this helps. let me know if you need any other help.