Looking for Office 365 license recommendation for personal use and domain name hosting

Greetings

I am assisting a friend who’s husband recently passed away. The husband ran a business, and both his and her e-mail were hosted with RackSpace. I am interested in moving the e-mail hosting over to Office 365 for my friend. The RackSpace account is pretty antiquated for features, so I feel she will get better e-mail service with Microsoft.

My friend does have a domain name, left over from her husband’s business, and is only used for the business's e-mail. She does want to retain the domain name for at least a few years until all the affairs with her husband’s passing have sorted itself out, so the M365 plan will need to include e-mail with your own domain name for two mailboxes.

I am looking at both the Microsoft 365 Business Standard and Microsoft 365 Business Premium plans. I like that the Microsoft 365 Business Premium includes Defender, so would include AV, but I see it also includes InTune, which she would never use. Could you combine both a Microsoft 365 Business Standard plan and a single Microsoft Defender plan together? Just to note, she is interested in having access to the installable versions of Outlook, Word, Excel, etc

The other thing is my friend isn’t running a business. The office 365 account would be strictly personal. She wouldn’t have any of the expertise to set up polices and rules for Defender and other security situations. Ideally there would be a Microsoft plan that offers e-mail hosting with your own domain name, access to install the click-to-run Office, and antivirus and security that is mostly configured out of the box

If anyone can give me some suggestions on an ideal Office 365 plan that would fit this category, I would be much appreciated.