Your question leaves a little to be desired, but it sounds like you don't want the DHCP daemon to start automatically at boot. What you can do is create a small script that disables 'udhcpd' and will auto-run at startup (see Chapter 8: Application Auto Run at Startup). If you create a symbolic link to your program with the 'S00' prefix (ex: "S00myapp-init"), it will run before any other scripts.
#!/bin/bash
# myapp-init: Prevent udhcpd program from auto-starting
# rc[0,1,6] kill the programs, so leave be.
for rc in 2 3 4 5; do
rm -f /etc/rc${rc}.d/*udhcpd
done
myapp-init.bb snippet:
do_install() {
install -d ${D}${sysconfdir}/init.d
install -d ${D}${sysconfdir}/rc2.d
install -d ${D}${sysconfdir}/rc3.d
install -d ${D}${sysconfdir}/rc4.d
install -d ${D}${sysconfdir}/rc5.d
install -m 0755 ${S}/myapp-init.sh ${D}${sysconfdir}/init.d/myapp-init
# run this script before any others
ln -sf ../init.d/myapp-init ${D}${sysconfdir}/rc2.d/S00myapp-init
ln -sf ../init.d/myapp-init ${D}${sysconfdir}/rc3.d/S00myapp-init
ln -sf ../init.d/myapp-init ${D}${sysconfdir}/rc4.d/S00myapp-init
ln -sf ../init.d/myapp-init ${D}${sysconfdir}/rc5.d/S00myapp-init