represent multiple entities to one entity relationship
Don't use an attribute value to indicate what entity a person owns. Instead, take advantage of the relational nature of the database in your queries. Remove the owns column from person and find related entities by joining the tables:

SELECT 
p.id AS person_id, p.first_name, p.last_name,
h.id AS home_id, h.no_of_rooms, h.area, h.city,
c.id AS car_id, c.make, c.model, c.color
FROM person p
LEFT JOIN home h
ON p.id = h.person_id
LEFT JOIN car c
ON p.id c.person_id
WHERE p.id = 1


A LEFT (OUTER) JOIN will select the desired person whether it owns any entities or not. You can then use logic in your application to detect which owned entities have values and which are NULL. Use an INNER JOIN to only select the person if it also owns one of the entities.