Phong Nha village has a strip of restaurants and cafes along the Son River, most attached to guesthouses. The range is limited but the quality has improved dramatically since the cave tours started drawing international visitors. Local bun bo Hue (spicy beef noodle soup) and banh mi at the morning stalls are the best cheap options. Several riverside restaurants do decent Vietnamese food — grilled fish and rice dishes are reliable anywhere along the main strip.
Easy Tiger, a hostel and restaurant that has been around long enough to become an institution among backpackers, does good Western food and holds its own socially in the evenings. Bomb Crater Bar and Cafe is another long-standing spot with live music on weekends. For something local, ask your guesthouse owner — the best home-cooked food in the village often comes from places with no sign.