Need Help with NPC Parent Dialogue

Hi there! I’m in the process of creating my first one shot (this will also be my first time DMing)

TLDR - I need my Players to care about their NPC mom between noon and bed time (in game time of course)

I think I have a pretty solid story and different pathways/outcomes laid out depending on the players actions, but I’m having a hard time with dialogue.

Long story short, the two players are brothers (in game and irl) who were adopted by the village leader after a swarm of giant spiders and driders invaded the village. This invasion killed the brothers parents and the village leaders son (hence the adoption).

The one shot will start at mid day in game, and I’m planning on another invasion happening when they go to rest for the night. During this invasion the village elder may die depending on how long it takes the brothers to get to her. If she dies BBEG takes the village relic and our brothers are now on a quest to retrieve the relic and get revenge for their parents. If she doesn’t die BBEG will flee with the relic still and village leader will send the brothers after the relic.

I have a short window to get them to actually CARE about their new mom and WANT to go out to avenge her/listen to her. Any tips on how to do this via RP? Have you had any memorable moments between players and parents in previous campaigns?