What to do in a case, when there is a nightly curfew from 8 o’clock at night. Going to mikveh or to daven in Yom Tov.
Right now shkiya is not that late, and she can go to the mikva before 8 o’clock, and be home before the curfew. Additionally there are times when it is permitted to break the curfew for religoiious reasons. Check out if this would be an exception. In the summer however, if indeed she can not go out at night because of the curfew, there is an option for her to wait until the 8th day of her 7 clean days, and go to the mikva even though it is daytime. Under normal circumstances a woman may not go to the mikva during the day, however in this situation she is allowed to go on the 8th day.
Regarding davening arvit on Yom Tov, if you don’t have a choice, the minyan can daven after plag hamincha, and you will just have to remember to say shema again. Even if it is the seder night. The issue is that you shouldn’t start the seder and make kiddush until it is nighttime, therefore you can daven with a minyan and then wait to start the seder.
Y:D 194-7, O:CH 472-1, M:B 472-4,5.