I need a way to convince my grandparents to let me stay with my boyfriend for the night?

Hi all! It’s been a while since I’ve been on, but I am in desperate need of all of your assistance.

In case anyone has forgotten, I am 21 and my boyfriend is now 23. We both live with our families; I with my grandparents and he with his mother. The rule for my family is that I am never allowed to stay the night with my boyfriend. The only two times where it was allowed was during Spring Break (because I paid for the trip before I told anyone and it was out of state) and once after a concert where we didn’t get back to my car until 2:30 am and I was too tired to drive home. His mother could care less if I stay over, she actually prefers it because it means less late night driving for both of us.

To start, no this is actually not a ploy to have a romantic night with my boyfriend alone on Valentines Day. Here is the situation: So we are in the south and have been snowed in for a few days. During this time, his mother has been feeling unwell and was unable to get medical attention. Earlier today, it got significantly worse and since the roads were ok, my boyfriend’s father drove her to the emergency room. Long story short, she has to have two different surgeries to fix a pretty serious problem. His dad is staying at the hospital with her for the next two days. The bf is staying at the hospital tonight too, but tomorrow he is going home. He is really stressed out about all that is going on with his mom. The doctors think they can fix the problem, but it’s still pretty serious and he doesn’t want to be alone at home tomorrow. I want to be able to stay with him just to keep him company and be there as support. I love him very much and I can tell how much this is stressing him out. Him being by himself will make things worse; he has a tendency to imagine the worse. Overactive imagination and such.

I feel like my grandparents will be receptive to that as a reason to stay with him though, I need something better to convince them. They are sympathetic to his situation, but just telling them that he doesn’t want to be alone will probably just result in a “man up” response. What can I do?