Person keeps knocking on neighbor’s doors because he "hears his girlfriend"

What kind of help does this person need? Who does he call? He still doesn't believe that she's not here. He keeps hearing her, and has not come to the conclusion yet that she's not here, and that what he's hearing is not real. If he doesn't choose to get help, what are the options of the tenants who live here? He's knocked on the house and garage apt thinking she's here somewhere. He lives in the lower garage apt. so It's not exactly trespassing.

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Which number to call from this link? Is Harris the best place to start?

reddit Houston mental health