No, she isn't the only one competing in seniors, but the others are much lower ranked. Laura Szczesna had their second Euros spot last year but finished almost last. She has an ISU PB of 144 and SB of 122, compared to 204 and 162 for Kurakova. Szczesna's highest score this season is 146 at a Slovakian competition this week. She has the technical minimum for Euros but not Worlds. Karolina Bialas has an ISU PB of 136. She took the bronze medal at Diamond Spin in October, with a score of 145, and scored 130 at Tirnavia Cup last week. She is entered for Warsaw Cup, as is Szczesna. Julija Polniuk has an ISU PB of 131 and scored 112 at Diamond spin in October. Agnieszka Rejment has an ISU PB of 102. She competed at Diamond Spin in October, scoring 108.
If your question was whether Kurakova is the only Polish woman competing in seniors, then no she isn't. If you question was really meant to be whether she is the only viable option for Poland, then she probably is at the moment. No-one else has the technical minimum for Worlds and Szczesna is the only other Polish skater with the minimum for Euros.