You did a good job, but degrees and a good education are far from the only marks of success when it comes to family life.
All parents fail to some degree so accept you didn't get everything right, no one ever does.
You seem to have taken in all your children now, despite their educational success. This means you didn't really raise them to be independent, especially your son.
You say your daughters don't allow your son to come home but it is your home not theirs. If they don't like your rules then it is they who should leave, surely?
Why do your daughters now need you? You don't say. I needed my mum too but I didn't need to live in her house.
I'm sorry this is causing you so much hurt but I think you should assert your rights and give them notice to leave. It is the only way you will have any peace, especially as they won't even speak to you. You are being abused by your daughters and need to get help.