Im not sure how i can ask this girl out. Any ideas?

I was planning on asking this girl out this past friday, but unfortunately, the day i was going to ask her out is the day she wasn't at work (i only see her at work). She was absent because her best friend's sister died the day before. So, it looks like i wont be able to ask her out any day too soon. I was thinking of asking her out in maybe a few weeks, but i found out that her last day of work is next friday. I really like her, and want to ask her out, but at the same time I dont want to be inconsiderate. I dont know who the best friend is, and i dont know the kind of relationship my crush had with her best friends sister. I already offered my condolence the day i heard about the death, but im not sure she was that much affected, considering it was her best friends sister, and not her own. I dont have a facebook (and preffer not to make one just to ask a girl out), and i rather not asking her out by calling her to her phone. Id do it in person instead. When is it best to ask her out?