If Momento is crashing when updating feeds this is likely due to a bug with the Flickr feed. To resolve this carry out the following steps:
1. Quit Momento
2. Turn on Airplane mode
3. Launch Momento
4. Go to Feeds > Manage > Flickr
5. Disconnect the Flickr feed
6. Close Momento
7. Turn off Airplane mode
This should prevent the issue reoccurring until we have issued a fix to resolve this.
Sorry for any inconvenience this has caused.