MRI on foot showed complete tear of central cord of plantar fascia with lateral and medial fascia intact with 2cm fibroma in arch. How to treat this?

Torn Plantar fascia. You should be immobilized for a short time to take pressure off the injury, but this is a ligament tear, and rest and possible anti-inflammatory therapy (including possible cortisone injections) would be of benefit. The ligament does not need to be repaired; in fact, a 'controlled tear' of the tendon is the preferred surgical method for treating plantar fasciitis. You will likely need orthotics.
Less is More. Plantar fascia tears can be painful. Treatment with ice, rest and elevation are part of the recovery. Non weight bearing may be necessary for a few days. Crutches may be helpful early on and eventually a ambulatory walking boot may be needed. The fibroma seldom causes an immediate problem and can wait to be addressed. This type of injury can take time to heal so expect several months recovery.