The best number to memorize is 911. It is what kids are taught as soon as they have some understanding of the world they live in. For almost any personal emergency, it is okay to call 911 (health, theft etc). If there is an emergency situation and you need your family to visit you, then the US consulate grants visas within hours. There is a procedure in place on the consular website. Typically, in such situations, the International Student Office (ISO) will help. It is mandatory in my opinion to inform the ISO in case of any emergencies. The ISO is an international student’s best ally.