I don't know what's available in Lakewood, and it might be too late for @avromie7's grandmother. My unequivocal suggestion is an appropriate senior living facility that has sections for independent people, assisted living, and nursing unit.
That may be the best answer, but to a different question.
You said that you reached that conclusion based on what you thought would have been best for your mother, and it may be what you imagine you'd want for yourself in the distant future, but it's not necessarily what would allow others to thrive. Cost, location, quality of life, and personal preference may prevent many from living in the sort of facility you describe. The problem of where to live when old, like the problem of where to live when young, has no one-size-fits-all solution.
The specific question here was how to improve the quality of life of someone who decided to live in a residential neighborhood near family.
A second best would be an adult daycare. It's important to have friends in a similar stage in life.
This answer, and others here, are good suggestions of activities she might engage in. My previous response was directed to the specific issue of how to help her find a solution to transportation needs, which may hinder her ability to engage in those activities.