What made the narrator think that his mother and Mrs. Mendis were not in good terms in bringing tony home?

The narrator senses tension between his mother and Mrs. Mendis when they discuss bringing Tony home from boarding school. His mother seems to be impatient and disagreeable, while Mrs. Mendis is more concerned about what is best for Tony. The narrator can tell by their body language and the tone of their conversation that they do not necessarily get along well.