Bed bugs. pest control companty dilemma - 1 treatment or 2 treatments required?

Hi, I got a quote from 2 different pest control companies due to bedbugs my tenant found. One company said it is enough to come once and treat it once and gave lower price. another company said 2 treatments are required as first tretment will not kill bedbugs eggs. who is right? is 1 treatment or 2 tretments required? THANKS.