We all know that OSPF is a link state protocol but in which condition it works as distance vector ?

Distance Vector protocol like RIP uses hop-count.

OSPF being purely Link-State protocol, doesn't have Hop-Count as a field in it's Header. So in no condition does OSPF work as distance vector.

EIGRP is Hybrid since it uses Hop-Count. Here hop-count is not as a metric but to limit the number of routers in cascading (Default is100 & can go upto255 hops).

This provides a safety mechanism that breaks any potential count-to-infinity problems. It causes the IP routing software to advertise as unreachable routes with a hop count greater than the value assigned to the hops-number argument.

Hope this helps.