Sherlock says to John, “I Don’t Have Friends But Have One”
 
Now I would think that Mrs. Hudson, Molly, and Lestrade are also his friends. It is true that he does not have a close relationship with them the way that he does John. However, they are people who would help him in a time of need and I think he would in turn do the same for them.
 
Of course, we all have our own views about what makes someone a friend. So feel free to disagree. That said, I would think that the one value that exists in any friendship is loyalty and they certainly have that.