if they have been paying your rent on time they are good tenants

if you just offered to renew at the same rate, you should not go back on it. it's not good business. I wouldn't do that if I were you. I also feel bad for family with 5 little kids to have to go out looking for new place to live in such a short time. If you offered the same rate, that means you were fine with taking that rent. I don't think it's good idea to change now.