How can I add drama when I write about someone slipping on clothes?

There is no drama in putting on clothes. Where the drama could arise is from her thoughts as she dresses. In truth you could skip this whole scene unless you really need to use this scene to explore the character's grief concerning the details of the deceased and some of her specific memories... so long as these add something to the story and don't just needlessly drag it out. If she goes to a funeral, it can be safely umed that she put on clothes.