Why don't you take the subway to Xinjiekou and take Line 2 to Daxing Palace?
After that, take Exit 3 and go in the opposite direction. Turn in the alley in front of that tall building and go to the end. Hongfu noodle restaurant is on your left.
If you want to follow the way upstairs, then after you get off the No.44 bus, cross the street and enter the nearest alley, and go straight through the food market, you will find the board of Hongfu noodle restaurant.