The Rebbe acknowledges the letter and mentions praying at the Ohel. He advises giving tzedakah during life rather than postponing it, citing the Frierdiker Rebbe’s view that good should not be delayed. While halacha limits giving beyond a chomesh, exceptions exist. He encloses a publication for wider sharing.
https://www.torahrecordings.com/rebbe/igroskodesh/014/005/5147