Sorry to hear about your friend but unfortunately, there is very little you or anyone can do for him since he left the country. The DREAM Act, in its current form, does not include any provision to grant legal status to children who've grown up here but left before the law was passed. The issue is too contentious in itself and I fear that this provision will be a deal breaker if it is included.

It seems that your friend's parents didn't have legal status, i.e. a green card, but at some point they had an employment authorization card. An employment authorization card (EAD) is just a card that grants a person the right to work temporarily. This card is usually granted if the person has applied for legal status and is awaiting the processing of their application. The EAD is only granted temporarily and has an expiration date after which they person is no longer legally authorized to work. More than likely, your friend and/or his family obtained their Social Security cards and driver's licenses when they obtained their EADs. The EAD permits a person to obtain a SS card and many states also grant driver's licenses to people who have EADs.

Nevertheless, the EAD doesn't legally permit a person to stay indefinitely. Its a temporary measure. It seems that your friend's family weren't able to obtain a green card, which confers the permanent right to live and work in the United States.

Your friend's parents are obtaining their green cards through a process called consular processing. Normally, any immigrants who are seeking to obtain immigration visas and/or green cards must apply from their own country to the U.S. consulate of their country. That is what your friend's parents are doing. If all goes well, then the parents will obtain their green cards and be able to immigrate to the United States.

Unfortunately, if your friend was undocumented for more than a year after his 18th birthday, then he is subject to a 10 year ban upon leaving the U.S.
The ban is cruel and completely arbitrary but that is the fault of the immigration system. Very few Americans know about the archaic and arbitrary nature of our current immigration system yet all immigrants have to deal with this at some point in their efforts to immigrate to the U.S.

I would recommend that your friend obtain his nursing degree in the Philippines and then obtain a Master's degree or its equivalent. There is a chronic shortage of health care professionals in the United States and immigration law recognizes this fact. A good lawyer may be able to waive the 10 year ban if your friend can find a employer willing to sponsor him, such as a hospital or clinic. The lawyer can claim that your friend's health care skills far outweigh any benefits that the 10 year ban would provide. The case is especially stronger if the sole reason for that 10 year ban is because of unlawful status and not due to any criminal or insurrection activity.