1031 Exchange or 121 exclusion or both??

[Ricardo P.]

Ladies and Gentlemen, 

I have a landlord friend of mine that lives down the street and is getting roasted due to covid 19 and a tenant who hasn't paid rent since February 2020. He lives in a small 4plex apartment in which he occupies one unit with his wife and kids.(3bed house) He's been living there for 4years and planing on selling and buying a SFH. 3 units will be delivered vacant at the close of escrow. Tenant who hasn't paid will be the only to stay in the property. Can he use a 1031 exchange? Or 121 exclusion?? Or maybe both?? Let's say he rather just sell his property out flat how much tax is he looking to pay when he sells? 20% or is it 25%?? I understand if you file single your exempted up to 250k tax free on your primary residence but I'm not sure if this applies to multi unit property.
Sadly he’s looking into walking away from this business due to the rules and regulations California has set during covid 19. What other way can he be able to sell and buy his home? Any help would be appreciated. He’s an older dude paying the mortgage on his own. I’ve been trying to help landlords around my area in any way possible. Specially when tenants are taking advantage of this situation