If she wants a lens just for the trip, consider renting. I’ve done several rentals with www.lensrentals.com and they’ve been very easy to work with.

A neat, inexpensive lens for the 60D is the Canon 40mm f2.8; makes for an easy to carry combination.

https://www.bhphotovideo.com/c/product/870179-REG/Canon_40mm_f_2_8_EF_Pancake.html