My grandma won’t let me sleep over my friends house

Hi everyone! I love with my gma! She knows my friend. I hung out with her this week and we ate and talked of course. Before going out with my friend, I told my grandma I’m going out with my friend, she said are you coming back? I said yes why wouldn’t I? And she said I don’t know so then I asked her would you ever let me sleep over her house? She said “hmmm idk about that because her parents are weird” and I said first of all, her moms bf doesn’t even live there. I just feel like I can never have a life! What should I do? Btw I’m 20 and turning 21 this October. Has your grandma or parents ever did this to you? What did I do? Should I just go or text her tomorrow after work asking if I can sleep over? Or should I just go since I’m an adult Sbd she won’t like anything I do anyway. Let me know thanks plus I was going to come back Mother’s Day and treat her then go to work after.