Vernon Davis is helping a family cope with the tragic loss of their son by giving them Super Bowl tickets ... telling TMZ Sports he wanted to, "Bring some joy to their spirits."
The story is super sad ... 17-year-old Ryan Howey was a normal football-loving teenager until he was suddenly diagnosed with brain cancer last May.
Howey's illness was gripping ... the poor kid had to go through chemo and radiation 5 days a week for 6 weeks just to start treatments -- and even needed more rounds of chemo after that.