My husband has a large venous foot ulcer. What are his treatment options?

Compression. Local wound care in combination with multi- layer compression will start the healing process. More importantly, an evaluation of the leg veins with an ultrasound and treatment of any venous insufficiency will help hasten the healing process and prevent recurrence.
Leg Ulcer. I would add that a comprehensive evaluation by a wound center would be in order. The key to venous disease is compression. Access to vascular surgeons that do venous repair may also be in order.
Combination approach. The mainstay of venous ulcer treatment is compression. A good place to start for that would be a wound care center. Never let the compression get in the way of an evaluation for the underlying venous cause though. Treating the veins will speed up the healing process and help to keep the ulcer from returning.