Should I redirect 404 to homepage?
404s should not always be redirected. 404s should not be redirected globally to the home page. 404s should only be redirected to a category or parent page if that's the most relevant user experience available. It's okay to serve a 404 when the page doesn't exist anymore (crazy, I know).
How do I redirect my 404 page to the home page in WordPress?
To enable the plugin, go to Settings >> All 404 Redirect to Homepage settings page. Then set the 404 Redirection Status to Enabled. Enter the URL of your homepage in the Redirect all 404 pages to section to redirect all 404 pages to your homepage. Click on Update Options button to save the changes.