首先确定一点：
摆脱孤独：比较常用的是 get rid of loneliness 或者 out of loneliness.
loneliness前面可以不用加the.
这里的让和使用help很贴切.
They help old people (to) get rid of loneliness.
Old people are helped to get rid of loneliness by them.实际中不常用这种被动语态.
Old people get rid of loneliness with the help of them.