My girlfriend has a WordPress blog for a while now, but when we check tools like websiteworth or woorank, it tells us that she has no twitter or G+ account, which is false.
Is there a way to "bind" her social network accounts with her blog ?
There is no such thing as binding social networks to a website. Basically, if those tools (whose values is debatable. I think they're worthless) don't work, they don't work. Contact the tool owner and let them know their tools shortcomings and maybe they'll fix it.