A federal grand jury has indicted Monica Cannon-Grant, a high-profile local activist in Boston’s racial justice movement, and her husband on allegations they defrauded donors of the nonprofit they founded, Violence In Boston; committed unemployment fraud; and lied to a mortgage lender, prosecutors announced Tuesday. Cannon-Grant, 41, and Clark Grant, 38, were charged in an 18-count indictment alleging the couple spent financial donations to the nonprofit on themselves, using the cash to pay for hotel reservations, gas, restaurant meals, food deliveries, nail salon services, and personal travel, while concealing their transactions from bookkeepers, directors, and financial auditors.