Pulse Down a line with Series terminations between transmission lines
As all connections are completely matched and there should be no
  reflection?


No they are not. Point b looking from left to right should terminate in 50 ohms but you have 50 ohms in series with the 50 ohms of the t-line between c and d. This means you are terminating b in 100 ohms. So no, the termination at point b does not match the left hand t-line.

And clearly this is the case if you think about it - if b and c were shorted then you would have one continuous t-line between a and d and then it would be a perfectly matched line.