adblock doesn't belong to DHCP at all ... it's all about DNS hijacking. At minimum you need a running dns backend on your LEDE box. For dnsmasq configuration without DHCP see here.
if adblock is running fire up e.g. a nslookup query ...
nslookup doubleclick.net
Server: 127.0.0.1
Address: 127.0.0.1#53
** server can't find doubleclick.net: NXDOMAIN
** server can't find doubleclick.net: NXDOMAIN
for log file checking use logread ... e.g. logread -e "dnsmasq" or logread -e "adblock"