I graduated in Dec 2009 and my mom got multiple tourist visa for my graduation for 5 years but she couldn't make it for that day due to financial problem. I have heard that she has to come within 6 month of date of visa issue otherwise visa will not be valid. Is that true? or can she come later because I am thinking to call her after 2/3 months or a year? Please suggest me if anybody has any experience or information regarding this.

This is not true. She can come any time before the VISA expiry date, but she cannot live for more than six month at a time. If she needs to live for more than six months at a time, it can be extended though.

This is not true. She can come any time before the VISA expiry date, but she cannot live for more than six month at a time. If she needs to live for more than six months at a time, it can be extended though.

Yes, she can come anytime. One of my friend's father came to US after 3years. 

kissna & colo, thank you so much for your reply. 

One of my friends dad came to visit him after 3 years too but his dad was here before (during graduation). I have heard the same thing that you've heard, if you do not enter US for the first time within certain timeframe, the visa will be terminated. So make sure about that.

no worries...my parents came like 3 weeks back and their visa was granted more than 10 months before for my graduation. I was replied from US embassy that they can come anytime after the multiple visa is granted......there is no deadline for entry as long as its multiple entry....

She can come anytime, but her entry date has to be before 6 months of the VISA expiry date. 

Where did you get the tickets from? I need to look for my parents......