You can use the RANDGEN call, which includes optional arguments for the mean and Std Dev. You first need to allocate a vector to store the data:
proc iml;
n=10;
E = j(n,1);
do i = 1 to 50;
call randgen(E, "Normal", 0, 4);
end;
You can also get all 50 variables at once. Each column of the following matrix contains a sample from N(0, 4).
E = j(n,50);
call randgen(E, "Normal", 0, 4);
For comments on generating random vectors efficiently, see
http://blogs.sas.com/iml/index.php?/archives/9-Efficient-Sampling.html
For a description of how to generate 50 variables that each have a different distribution, see
http://blogs.sas.com/iml/index.php?/archives/117-How-to-Sample-from-Independent-Normal-Distributions...