Q: Is it permissible for a woman to follow the janazah of her husband? Burial is to take place in 4 hours. My mother wants to know (text)
A: It is makrooh-e-tahrimi for her (a woman) to follow the janazah. (Darr-ul- muktar. Shaami vol. 1 598)

It remains better for your mother to pray for the one that has passed away. Her patience would reap her greater reward. To fight the urge to do a wrong when most tempted to do so, also to fight the urge to do a wrongful action when one has the ability to do so would bring her supreme spiritual benefit. Sabr and good deeds done at its onset of a calamity brings more reward than done later {when things are better}  (extracted from Hadith.)

May Allah (SWT) bless the deceased with jannah-tul-firdose (ameen.)

Allah Certainly Knows Best