K.P.
Unfortunately, I think your mother may not even realize what she is doing.
Say to her this- Do you realize if a white person was to say to you "I went to Calle Ocho and there were only a hand full of black people. It was very nice." You would have been enraged? I think if you approach her in that manner you may have some impact on her thinking. Reword her statements int his way. If she strives to teach diversity she may just need to rethink how she approaches her own thinking.
Diversity to some means "Lots of people like me." True diversity means "Looks like the population as a whole." It sounds like she prefers the first definition. If we push diversity so far that we begin to eliminate an entire different segment of the population based on race then we are still being racist.