One option would be a HP dv7t - about $765 with Blu-Ray player upgrade. http://www.shopping.hp.com/webapp/shopping/computer_series.do?storeName=computer_store&category=notebooks&series_name=dv7t_series
Dell Inspiron 17T - $900 with Blu-Ray player.http://www.dell.com/us/p/inspiron-17r-combo-mod/pd?oc=dndon27b&model_id=inspiron-17r-combo-mod
You'd probably be able to get 3.5hrs out of the batteries while surfing the web. 3.5hrs while watching a movie? More like 2.5 for the extra power demands for that.
How firm is that Blu-Ray player requirement? Usually you get Blu-Ray for it's 1080 playback. And 1080 17" LCD screens aren't quite in your budget. Can your mom get by with HD (720) movie playback? It's still excellent quality, and you'd save about $100 or more, plus the lower cost of HD vs Blu-Ray movies.