[R] predict.lm - standard error of predicted means?

[mark salsburg]

Can someone please refer me to a function or method that resolves this
structuring issue:

I have two matrices with identical colnames (89), but varying number
of observations:

matrix A                                matrix B 

217 x 89                              16063 x 89

I want to creat one matrix C that has both matrices adjacent to one
another, where matrix A is duplicated many times to create the same
row number for matrix B, i.e. 16063.

matrixA matrix B
matrixA
matrixA

so matrix C will be 16063 x 178

I've tried cbind() and merge() with no success..