Choose two or three scholarly historical monographs offering different interpretations of the same or a related topic. Discuss the ways in which the interpretations of the historians concerned reflect differences in 
The evidence used. 
Method. 
Perspective of the individual historian (e.g. national, ideological/ political, religious, gender, etc.). 

What argument is the author making? Moreover, do the two monographs each offer a different interpretation of the same issue?

The task is asking you to compare two different interpretations of a similar topic and explain why the authors reached these different conclusions. 

I would perhaps suggest comparing the interpretations of JJ Saunders (The History of the Mongrel Conquests, 1971) with the interpretations of Leo De Hartog (in either the book you've identified or Russia and the Mongol Yoke, 1996) with regards to the nature of and/or the significance of the Mongol conquests. Do these authors see the nature of the mongol conquests/invasions to be different? Ie. more or less oppressive/violent? Do they draw different interpretations of the long-term implications of these conquests? 

You should also ask yourself, why did these authors draw these different conclusions? What were their books trying to achieve? What evidence did they use and how?