Your mom needs "charity care". Talk to social worker in hospital

The law states ER is obligated to treat everybody irrespective of ability to pay. It is based on your mom's personal income. If you can prove your mom's income is below the poverty line, the hospital cannot charge your mom much. At the hospital I worked, countless foreigners especially those from South America, got "charity care" even if they are illegal and undocumented. There was a woman who had her father with terminal lung cancer come from Russia on tourist visa. He was treated with all sorts of chemotherapy and paid little, because his income was low. Some people went to ER directly for any illness, because they pay little for ER care as opposed to outpatient treatment, if they were poor. People from South America flew to US just to get medical care for "free", because they cannot afford care in their own country. Some directly came to the hospital from the airport to get treatment started because they were so sick. US law states hospital is obligated to treat everybody, whether they can afford or have legal status. I recommend you talk to professional people who are familiar with healthcare law. You can request to talk to social workers in hospital. They should be able to help you.