Using Car* (*more then 1 letter) and Monaghan a list of 43 names came up. Link: https://www.johngrenham.com/places/simple_results.php?place=Car*&submit=Submit&county=Monaghan . Could Mc Ross refer to a person there ? quit a few people by the name of Ross in Monaghan. The name Mc Crof or Crof does not appear in any Irish records but the name Crop does just 1 person in Co. Monaghan.
The first instance appears to read "Ireland McRoss Carruk" (or Ireland McRoss Carrick)
The first instance appears to read "Carick McRoss Ireland" (that's an old fashioned double s, not an F). The "Carick" is not clear and could be interpreted in other ways.
As you deduced, both probably refer to Carrickmacross, County Monaghan. https://en.wikipedia.org/wiki/Carrickmacross
You did not state who was listed in these census records, but if you have not already done so and the dates fit you might want to check the Catholic marriage and baptismal records from Carrickmacross (1858-1880) to see if the name appears. Maghaire Rois, Clogher - Catholic Parish Registers at the NLI