How does one charge their mother for rent, food and utilities after she's had a stroke?

We don't know, you'd need to ask him.  Keep in mind, dude had all of his mother's resources at his disposal.  Dude did not have an agreement with anyone written or otherwise to be paid or reimbursed for voluntarily taking care of his mother!!!

Now this:

Homeless man in shed illustrates Charlotte’s toughest cases

[snip]

“She’s an African-American woman, educated and works a 9-to-5 job in the corporate sector. He’s an older white male with limited education, who grew up impoverished,” she said. “Their friendship seems to erase lines between race, class and gender in a way that is powerful.”

Pierce and Robinson first met when she was attending church at Community Outreach Christian Ministries, which was then working with the Harvest Center to house up to 20 homeless people. Pierce was in that housing program, but he was kicked out five times because of his drinking, she says.

“There is something about Bear, an almost childlike innocence that makes you want to help him,” she says. “That innocence got him taken advantage of a lot on the streets.”

Robinson’s friends say she has a reputation for bold acts of kindness, but many were surprised to learn she was allowing a homeless man to live on her property. 

Read the article:

http://www.charlotteobserver.com/news/local/article20086371.html

R