She needs the anti-phishing filter, the anti-malicious app & URL filter, and will want useful features like Cortana, predictive search, page compatibility modes, allowing websites/apps to ask for her location (e.g. Google Maps), and her files to be backed up when her computer fails.
You can argue if certain things help your "grandmother" (e.g. telemetry, advertiser IDs, etc) but this seems like to throws the baby out with the bathwater.
PS - Windows 10's defaults could be better. But this takes it to the other extreme, disabling legitimately useful functionality (in particular security focused functionality).