Your spec that the "script should run on A server and ftp the file to B remote server and then the same script (emphasis supplied) should run by logging into B server" -- taken litterally -- can NOT be achieved by any legitmate means of which I'm aware.

yes, "logging into B server" is something the script on the A server can do... but it can NOT execute itself on the B server (except by injecting instructions to the CPU(s) there to use its own code, streamed to B after the injection - a malware technique).

Rephrasing, for emphasis:

1. If the code on A can't move itself to B and execute there, and if there's no route between A and C, your transfer scheme is not feasible.
2. If you overcome those difficulties, your scheme is unsafe or unwise.