Final answer:
Granny saw a deer limping.
Step-by-step explanation:
In the given passages, the object that Granny saw limping was a deer.
In the first passage, it is mentioned that Granny saw a strange moving object that she could not name, and then it is revealed that the object was followed by more creatures and that they were all moving towards the brook.
This indicates that the object Granny saw was most likely a group of deer moving together.