Is Gaara able to control sand because of his mother or shukaku (the 1 tails)
Sand manipulation is not something limited to the Shikaku. Throughout the series we have seen several sand controllers.

One of the most notable applications of sand manipulation would be Kankurō's manipulation. Where he masks his puppet as another person, in chapter 42.

However, the Shikaku does help. Just as how the nine tails allows naruto to tap into it's chakra, the shikaku allows something of a similar sort. Which effectively allows Gaara to manipulate more sand. 

So to answer your questions


  Is Gaara able to control sand because of his mother or shukaku


No, as several others have also shown control of sand.


  friend of mine told me that the sand is Gaara's mothers will and that's why he carries it around cause the sand is special


This is correct. Upon dieing his mother imbued the sand which Gaara carries along in the gourd with her will. This sand will protect Gaara regardless of his will, a technique also known as sand shield