These 2 features are not currently implemented in Tweetinvi. I can put them at the top of the priority and release them within Tweetinvi 0.9.4.0.
As the first endpoint returns multiple information here is how you need to extract the data until the feature is released :
// Get json
var json = TwitterAccessor.ExecuteJsonGETQuery("https://api.twitter.com/1.1/blocks/list.json");
// Get Tweetinvi Object
var jobject = TweetinviContainer.Resolve<ITwitterAccessor>().ExecuteGETQuery("https://api.twitter.com/1.1/blocks/list.json");
var blockedUsersDTO = TweetinviContainer.Resolve<IJObjectStaticWrapper>().ToObject<IEnumerable<IUserDTO>>(jobject["users"]);
var blockedUsers = User.UserFactory.GenerateUsersFromDTO(blockedUsersDTO);
I was not able to find the url
https://dev.twitter.com/docs/api/1.1/post/mutes/ that you posted
that your referenced here.
Hope this serves you well.