医院出个证明吗?
-Yes, and the Dr. letter, hospital bills,etc. She can apply for the SB-1 visa from the US Consulate in Guangzhou. You may contact the other US Consulates/Embassy in China to see whether the SB-1 visa is availble somewhere besides the US Consulate in Guangzhou.
这样的申请只能是一次吗?
-Yes. Read these links:
http://guangzhou.usembassy-china.org.cn/*****1_visas_returning_residents.htmm
http://www.immihelp.com/greencard/returning-resident-visa.html