To whom it may concern,
I will start with some questions:
1.) Old PCs meaning 32bit? If yes then the OS can be only 32bits, even if the machine is 64 bits or you would have two ISOs, one for 32 and one for 64 bits. There could be a small check app running during boot and based on this would start the 32 or 64 bit ISO, but this would blow your budget. Secondly keep in mind that minimum memory for desktop versions of new ubuntus, 14.04, 16.04 is 512MB. So if the old machine has less than 512MB it won't work for a desktop ubuntu.
2.) php with apache or what is php needed for?
3.) openvpn client or server? Based on your answer there would arise more questions.
4.) ssh, server or client?
5.) "and make sure if i run live iso on 2 or more pc not same id all PC ", what ID?
Before I accept the project I would need answers to the above questions.
I have been customizing distros and making my own distributions based on LFS for a lot of years now. So creating a custom made ISO is not a problem, the question is for what you are going to use it.
I am at your disposal for further questions.
Regards,
Daniel