Brother in law mental state - options

Hello,

Looking for advice on how to handle a situation that just gone downhill for about 7-8 years. I have a brother in law who came to US on an international student visa in 2010 and I had not really known him before that. I believe he needs help of a mental health professional. He is currently living on the road and requesting more financial help from his mother so that he can move to a hotel.

List of events/ suspicious signs:

-Refusing to get drivers license (fear of not getting license?) yet still driving a car for few years.
-His dad passed away while he was in US 2010 and his family insisted that he complete his education and stay in US
-Upon visiting him mid-way through his graduate studies on east coast, we noticed some form of hallucination where he believed he was under threat. He sought treatment at university counseling for some time and it seemed to be helping him. However when the counselor moved out of town he reverted to his original state and didn't seek further treatment.
-He started sharing less and started to blame me & husband for not helping enough. Became extremely stubborn, rude and only wanting financial help. Not knowing how to handle the situation with his mental state, we also stopped communication.
-Refusing to graduate in 2014 and either move back to home country/ apply for residency in US process for internship etc.. The conversation shifted to doing phd. However we all knew his mother can't support university education for a phd and begged him to graduate and look for job. It was almost as if again he wasn't ready to move on with life. He just begging me to support his monthly tuition. I paid once (~ $4500) thinking it might help him graduate . That wasn't the case. He stayed in US and let his student visa expire and went on some statement about doing phd (while illegal and not even enrolled in university..)

-Since 2014, till now his visa has long expired so he has been living illegally all the while using his mom to support his living expenses. Promises that he will 'fix' it all. I don't think he has left the 2 mile radius of his university area.

His mother was supporting his education financially/living expenses for the past 10 years and essentially there is no more money left to support from a foreign country. She sold her house and is at the very exhausting point as he continues to beg more money towards a non-realistic cause of "fixing it all"

Anyhow now he is on the road as my mother in law ran out of money, again refusing to leave his university area and come back to home country. She begs him to return to home country and he doesn't share much.

I am not sure what to do. My husband doesn't want any communication with him and hasn't talked to him for 6+ years. I feel sorry for him and his mother. If i go to meet him, he will most likely not meet me. With the shelter in place order and my young baby, i don't think travelling to somehow negotiate with him personally is an option.

Question: Can we use city social services to help him out of the street? I am not sure how to get him mental help either. I don't know how on earth to convince him to board the flight to his home country instead of living in US as a homeless.

Sorry long post, i am at a loss of what to do and if there is anything i can do to help the situation.

Appreciate your read. Thanks and be safe.