What do we learn about Mrs. Ascher's death in Chapter Four of the novel, The A.B.C. Murders?

In Chapter Four, we learn that Mrs. Ascher was struck down by a heavy blow when
reaching for Player’s cigarettes for a customer. She was murdered sometime between
5:30 a.m. when one man was in the shop to 6:00 a.m. when another man walked into
the shop.