Please help creating this iRule to direct subnets to different paths.

How about something like this?

Create a datagroup with the subnets above and call it, say "xyz_subnet" and this iRule should do it

when HTTP_REQUEST {
if {([class match [IP::remote_addr] equals xyz_subnet]) } {
    HTTP::uri "/XYZ"
} else {
    HTTP::uri "/ABC"
}
}

Hope this helps, N