I have a question about a cousin I'm worried about? (please read it)?

Most of the people I would have to say 99 percent of the people in my family went to college in my family and did something with themselves and are successful, but I have this one cousin who is almost 30 years old, doesn't have a driver's license and has never been on a date in her life and has cleanliness problems. Like she doesn't take showers, brush her teeth, or or her hair. My other two cousins from my aunt are just the opposite they take care of themselves and keep themselves in shape. The cousin with no license is in college, but she doesn't do anything and she weighs 200 pounds and is six feet two inches tall she's the tallest out of all the girl cousins and she just stays in her room on the computer. Everyone in the family wants to help her when we see her this summer. My cousin who has done something with her self and keeps herself in shape asked if she could talk to this cousin with all these problems. All my cousins are in their 30's I'm the youngest I'm 20 years old. It's just when my cousin who keeps herself in shape and who is sucessful asked the my aunt the mom of the cousin who has all these problems if she could have permission to talk to her and ask what she's gonna do with herself her mom said no and it would create too much drama. So as a cousin do I keep my mouth shut or rebel and try to talk to this cousin with problems and risk family drama or just stay out of it and let this cousin who's almost 30 act and behave like a helpless five year old till her parents pass away and she'll remain helpless.