Himem.sys is normally in c:\windows and c:\windows\command\ebd. Looks like you're missing the first one. Try this command from the dos prompt:
copy_c:\windows\command\ebd\himem.sys_c:\windows
(Don't use the underline_as I included that so the command would show on a single line. Replace the underline with a space.)
The other two files won't be in the ebd folder but it's possible they may still be in the windows folder. They may not have loaded because himem.sys didn't load. If you still get the error message try the dir c:\dblbuff.sys/s and then dir c:\ifshlp.sys/s and see if you can locate them elsewhere on the drive. If not I can email you the files.
If you need them emailed, do a VER at the dos prompt and post back what it says. That will tell me what version of 98 you have.
Anyway, try that and post back the results.