Looking on the internet deeply has found these results:

a friend of my mom is the most popular phrase on the web.

a friend of my mom's 13,850 results on the web	a friend of my mom 17,600 results on the web More popular!
Some examples and use cases from the internet:	Some examples and use cases from the internet:
"Who is this again? You're a friend of my mom's?” I didn't know the woman on the other end of the line and couldn't make sense of what she was saying. A friend of my Mom's from church recently posted this picture on her facebook. The woman is a redskins fan and when she posted this my Mom was so upset. 23 May 2011 ... (un amigo de mi madre) Tengo 21 y me parece que por aquí sólo las personas nacidas antes de los '70 van a decir "a friend of my mom's.". This cake was for a friend of my Mom's. This idea was taken from a picture the bday girl liked that my Mom found. Gumpaste bottle, buttercream ... Wine bottle	A friend of my Mom's from church recently posted this picture on her facebook. The woman is a redskins fan and when she posted this my Mom was so upset. "Who is this again? You're a friend of my mom's?” I didn't know the woman on the other end of the line and couldn't make sense of what she was saying. 23 May 2011 ... No sé cuál es gramaticalmente correcta pero yo diría "a friend of my mom"(un amigo de mi madre) o "my mom's friend."(un amigo de mi madre) ... cleverbirdbanter.wordpress.com. a couple years ago a friend of my mom sent this to her with a sweet message: "This reminded me of your daughter" More ...

a friend of my mom's

13,850 results on the web

a friend of my mom

17,600 results on the web

More popular!

"Who is this again? You're a friend of my mom's?” I didn't know the woman on the other end of the line and couldn't make sense of what she was saying.
A friend of my Mom's from church recently posted this picture on her facebook. The woman is a redskins fan and when she posted this my Mom was so upset.
23 May 2011 ... (un amigo de mi madre) Tengo 21 y me parece que por aquí sólo las personas nacidas antes de los '70 van a decir "a friend of my mom's.".
This cake was for a friend of my Mom's. This idea was taken from a picture the bday girl liked that my Mom found. Gumpaste bottle, buttercream ...
Wine bottle

A friend of my Mom's from church recently posted this picture on her facebook. The woman is a redskins fan and when she posted this my Mom was so upset.
"Who is this again? You're a friend of my mom's?” I didn't know the woman on the other end of the line and couldn't make sense of what she was saying.
23 May 2011 ... No sé cuál es gramaticalmente correcta pero yo diría "a friend of my mom"(un amigo de mi madre) o "my mom's friend."(un amigo de mi madre) ...
cleverbirdbanter.wordpress.com. a couple years ago a friend of my mom sent this to her with a sweet message: "This reminded me of your daughter" More ...