CJam, 15 13 11 bytes
A: rl"
B: <SP>
C: <LF>",(*SNq
Try it online in the [CJam interpreter][1].
How it works
e# A
r e# Read a whitespace-separated token from STDIN.
e# This reads the input up to the first space, but does not consume it.
l e# Read the rest of the first line from STDIN.
e# This reads up to the first linefeed and consumes it.
" e# Initiate a string.
e# B
<SP> e# Fill the string with as many spaces as there are copies of B.
e# C
<LF>" e# Terminate the string with a linefeed.
e# This serves as a delimiter for the `l' command.
,( e# Compute the length of the string minus 1 (to account for the LF).
* e# Repeat the string read by `l' that many times.
SN e# Push a space and a linefeed.
q e# Read the remaining input (i.e., the second line) from STDIN.
At the end, the stack contains the token read by r, the space produced by *, the space and linefeed pushed by SN and the line read by q. CJam prints all these automatically.
[1]: http://cjam.aditsu.net/#code=rl%22%0A%22%2C(*SNq&input=rl%22%0A%22%2C(*SNq