Terror at Red Wolf Inn (1972) on Netflix

Regina (Linda Gillen) is a lonely young college student. As the rest of the school is departing for spring break, Regina feels left out because she has nowhere to go for her time off. When she returns to her dormitory, she receives a letter informing her that she's won an all-expenses paid vacation to a small seaside resort. When she phones the number given, they tell her that she is to meet a small private plane that will take her to the resort that evening. With no time to plan, Regina hurries away without calling her family.