Scarlett Johansson was determined to have some “alone time” with boyfriend Nate Naylor before heading to Drew Barrymore’s weekend wedding in California. “The Avengers” star was dining at theater haunt Joe Allen with Naylor on Thursday when she saw her mother, Melanie Sloan, at another table, spies said. But, “Scarlett went to greet her mom without Nate, then returned to have dinner for two only,” our source said. The two “embraced at one point and looked very happy.”