I understand why you told your friend (and I would have done the same) but I have to say that there is some shocking ignorance misinformation on this thread, told as fact by people with zero RL understanding of MDMA or any other stimulant drug.
There have been a handful of deaths attributed to MDMA pills, since it came about in 1980s, which is nothing when you realise that there are about 517,000 habitual users in the UK (2010 figures). To put things into perspective, aspirin causes hundreds of deaths each year. Clearly, MDMA and whatever it is cut with is rather impotent as far as "dangerous" substances go.
Sure, all white powder can be cut with something else, but manufacturers and dealers of such stuff are not in the business of killing people. They want to make money. And as in all business, that is best done with happy customers who don't die because they have consumed your product.
I had to laugh at "cut with cement". Seriously?
What, because so many have recently died horrible agonising deaths because of a batch of MDMA cut with cement, of all things? Because you think it is so hard to find flour, baby powder, or a hundred other cheap and inoffensive substances that they would add cement to a pill? 
And re your asking your friend if her DD looked OK when she came home that night: It's perfectly normal that she thought her DD looked fine. She wasn't drowsy or drunk. She was perhaps a bit too alert and a bit too happy but would appear fine.
Tell your friend to look out for huge (dilated) pupils, even in a well-lit room.