Well my mom passed away about three years ago and we all get the checks but they go to my guardian. Their suppose to stop when you become an adult, but my guardian said as long as I stay in school I'm still a minor so it this true
And if so will I get the checks if I moved out of her home and live with someone else when I turn 18

To a certain point yes, From the SS code, "Under 18 unless he or she is a full-time student (no higher than grade 12) then, the benefits can be awarded to those 18 and 19.
Older than 18 if the child is disabled, but the disability must have started before his or her 22nd birthday.
".

well my mom passed away bout three years ago and we all get the checks but they go to my guardian. their suppose to stop when you become an adult, but my guardian said as long as i stay in school im still a minor so it this true
and if so will i get the checks if i moved out of her home and live with someone else when i turn 18

You are eligible to receive survivor's benefits until age 18, or until age 19 if you are enrolled in elementary or secondary school.

You can call the Social Security office to inquire about having checks made out to you - it may be that once you turn 18 the checks can be addressd to you regardless of where you live. See: http://www.ssa.gov/online/ssa-4.html

Thanks that really help :)