I hadn't seen your previous post before my last post. All the files you posted are in a regular Ubuntu /boot/grub/ directory. You are obviously missing the grub.cfg file and core.img although I don't think you would need core.img. If you have an installation of Ubuntu, you can look in its /boot/grub directory and see that you have only half the files in that directory. Did you just not post them all?
Read the link I posted above and check the link below, Section 12.3. Note at the end it tells you to reboot and run update-grub. Running update-grub from your system on the hard drive won't help. This type of installation is basically assuming an install on a hard drive. The pendrivelinux site has similar instructions.
I put some iso files on a flash drive, installed grub2 with the method above and copied/modified grub.cfg from an Ubuntu install to suit my purposes. Should not be that difficult but I don't know what your intentions are?