The provider must activate the VPNv4 unicast address family between PE routers. In an MPLS Layer 3 VPN, customer routes learned from CE routers are placed into VRFs on the PE routers. To carry those customer routes across the provider backbone without overlap, MP-BGP advertises VPNv4 routes, which combine an IPv4 prefix with a route distinguisher. Route targets then control which receiving VRFs import the routes.
Plain IPv4 unicast would not preserve customer VPN context and would not solve overlapping route separation. L2VPN EVPN is used for Ethernet VPN services and data center or Layer 2 VPN use cases, not classic MPLS L3VPN route exchange between PEs. Address-family multicast is unrelated to exchanging customer unicast routes between PE routers. Cisco MPLS VPN design relies on MP-BGP VPNv4 between provider edge routers, while PE-CE routing can be static, OSPF, EIGRP, BGP, or another supported method.
Therefore, VPNv4 unicast is the correct PE-to-PE address family. Reference topics: MPLS Layer 3 VPN, MP- BGP, VPNv4 unicast, route distinguishers, route targets, PE-CE routing.