Translation:My grandparents live far away from us.
I guess it's because it doesn't express origin. The grandparents are not coming from their houses, they are just there, if that makes sense? I guess "el" is not "from" in all contexts.
Pronoun shifts are driving me crazy in this course. No, don't take me wrong, I'm not bitching, just pointing out what it would be considered bad writing in English. This sentence starts with "my" and changes to "us" by the end. There should be consistency in pronouns used throughout a single sentence.
What if you live with some friends and are telling them about how far your grandparents live from you (plural)?
"Your grandparents live close to us? Well, my grandparents live far away from us"