Mariluz Diaz, a Bronx resident, arrived at the Bronx Food Stamp Office on a recent Tuesday morning, cane in hand, expecting the kind of wait she has grown used to. “Yesterday, I couldn’t sleep because I knew I had to come here,” said Diaz, 51. She had two hip replacements last year after arthritis forced her to stop driving a school bus. “I left my phone at home and I could have gone back to get it.