Broadcast is an important building block in ad hoc networks. Its challenge is to deliver a message to all nodes in the network for a reasonable cost in terms of message load and delay. Several context-aware broadcasting protocols have been proposed in order to meet this challenge, using location or proximity information in order to fine-tune retransmission decisions. However, existing protocols often target one specific setting and can reveal to be sub-optimal when settings change. Typically, optimal parameters for dense networks will differ from optimal parameters for sparse networks. To address this issue, we propose PLAN-B an adaptive proximity-based broadcast protocol that offers the possibility to define policies in order to adapt its parameters for different network settings at runtime. Our performance evaluations show that PLAN-B outperforms existing static and adaptive protocols in terms of message load in changing and unknown densities up to a factor of 2.