The general advice above on communication applies to to any kind of tutorials. However, the challenges for dissertation and project supervision are very different. At the time of writing, there is still some uncertainty about whether final year students will be offered extensions or an alternative task, so please check with your Head of School if you are unsure about how your students will be affected.
In particular, be aware that due to the coronavirus epidemic ” face-to-face (In-person) data collection and recruitment is suspended until further notice. This includes any research activity that requires you to be in the same place as your participants, either at a university space or elsewhere.” Guidance on alternative data collection and contingency plans for student research
So, depending on what stage they have reached, your students may be having to redesign their studies according to the guidelines, or they may be offered an alternative task, or they may already be at a point where they have completed any fieldwork and are writing up their findings.
In general, helping students to find out exactly what is expected, if that has changed, and then draw up a practical and manageable ‘to-do’ list is the main priority at this stage. Once they reach the next stage, commenting on drafts is often done via email even in normal times so may not feel so different.